temconsulting.comtemconsulting.com/committees/c63_24/committee_docs/C63.2… · Web viewNew and emerging technologies (700 MHz WCS, 1.7GHz, 2.3 AWS GHz, and 2.5GHz BWA): TDMA signal

ANSI PC63.24/D1.7, August 2012

IEEE PC63.24™/D1.7

Recommended Practice for

In-Situ RF Immunity Evaluation of Products,Instrumentation, and Control Systems in High

Reliability Installations

Prepared by the WG on C63.24 Working Group of the ANSI ASC C63 SC5 Committee

accredited by the

American National Standards Institute

Secretariat

Institute of Electrical and Electronic Engineers, Inc.

Approved XX September 2012

American National Standards Institute

Copyright © 2012 IEEE. All rights reserved.

Abstract: This standard provides recommended test methods and limits for assuring the radio frequency (RF) immunity of instrumentation and control systems that require a high degree of reliability in the presence of general use transmitters with transmitter power up to 8 watts.

Keywords: audio interference, EMI, immunity, interference, instrumentation systems, control systems, RF, RFI, susceptibility

________________________

The Institute of Electrical and Electronics Engineers, Inc. 3 Park Avenue, New York, NY 10016-5997, USA

Copyright © 2012 by the Institute of Electrical and Electronics Engineers, Inc. All rights reserved. Published 9 January 2012. Printed in the United States of America.

Bluetooth is a registered trademark in the U.S. Patent & Trademark Office, owned by Bluetooth SIG.

C63 is a registered trademark in the U.S. Patent & Trademark Office, owned by the Accredited Standards Committee on Electromagnetic Compatibility.

iDEN is a registered trademark in the U.S. Patent & Trademark Office, owned by Motorola, Incorporated.

PDF: ISBN 978-07381-5860-0 STD95873 Print: ISBN 978-07381-5861-7 STDPD95873

No part of this publication may be reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher.

iiCopyright © 2011 IEEE. All rights reserved.

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An American National Standard implies a consensus of those substantially concerned with its scope and provisions. An American National Standard is intended as a guide to aid the manufacturer, the consumer, and the general public. The existence of an American National Standard does not in any respect preclude anyone, whether he has approved the standard or not, from manufacturing, marketing, purchasing, or using products, processes, or procedures not conforming to the standard. American National Standards are subject to periodic review and users are cautioned to obtain the latest editions.

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Introduction

The use of electronic products and system requires that they have a sufficient level of radio frequency (RF) immunity to ensure that they operate at acceptable quality levels in their intended use environments. While fluorescent lights, microwave ovens, portable wireless devices, nearby commercial radio and TV stations and other RF sources have been part of the EMI environment for a number of years, interference problems with many types of equipment have been exacerbated by the recent dramatic growth in personal RF devices such as cellular telephones, wireless network connections, and cordless telephones. It is common today to have one or even multiple wireless devices transmitting in close proximity. Type testing, in which a representative sample of a product or system is tested in a lab, is a common method of evaluating the RF immunity of the design. However, type testing has its limitations. Type testing cannot insure that all manufactured samples of a product will have the required RF immunity. There is always some manufacturing variance and at times design changes may negatively impact the RF immunity. A second issue, particularly with large distributed systems is that it is difficult and sometimes impossible to replicate in a laboratory the actual configuration to be used. Differences between an actual installation and the configuration tested in a laboratory may result in significant differences between the RF immunity found in lab testing and that actually present in the installed system. This recommended practice addresses the need to evaluate the actual RF immunity of devices or systems, as they are installed and used. This is particularly true for larger, more complex systems which are too large to ever be setup in a laboratory in the same way they will be in a factory. Often such systems are custom installed to meet the unique needs of each customer, which further changes it from the laboratory sample that was type tested.

A second distinction of this recommended practice is that it supports adaptation and coordination of various mitigation measures. A device may be tested inside an additional shielded cabinet, if that is what a plant operator wants to do to insure a very high level of RF immunity. Other variations between the laboratory tested configuration and an actual installation can be evaluated to insure that the desired level of RF immunity is present.

Another contribution of this recommended practice is that is more closely replicates the actual RF threats that equipment will be explosed to. Radiated immunity tests are performed with a spacing of 3 m (or 1 m) between the device and the radiating antenna. However, in actual use, the separation between devices is very often just centimeters. This is particularly true for portable wireless devices. There is nothing to control how close or far a cell phone or other transmitting device will be from other equipment. Furthermore, the current radiated immunity testing, based on the method described in IEC 61000-4-3, uses amplitude modulated CW signals, and only in specific cases is pulse modulation applied. Modern wireless communication devices use increasingly complex digital modulations. These broadband signals pose a different interference potential since the exposure mechanism is very different from the one in a test where a simple CW or amplitude-modulated signal is used. This matter is further compounded by the dependency of the equipment under test (EUT) behavior on the data rate and protocols employed by interfering devices operating in the near area.

Thus this recommended practice was developed in response to the recognized need to supplement type testing with in-situ evaluation when there is a strong need to insure adequate RF immunity in the actual installed equipment. It provides methods that may be used after equipment is delivered and installed.

Laws and regulations

Users of these documents should consult all applicable laws and regulations. Compliance with the provisions of this standard does not imply compliance to any applicable regulatory requirements. Implementers of the standard are responsible for observing or referring to the applicable regulatory

ivCopyright © 2011 IEEE. All rights reserved.

requirements. IEEE does not, by the publication of its standards, intend to urge action that is not in compliance with applicable laws, and these documents may not be construed as doing so.

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For more information about the IEEE Standards Association or the IEEE standards development process, visit the IEEE-SA website at http://standards.ieee.org.

Errata

Errata, if any, for this and all other standards can be accessed at the following URL: http://standards.ieee.org/reading/ieee/updates/errata/index.html. Users are encouraged to check this URL for errata periodically.

Interpretations

Current interpretations can be accessed at the following URL: http://standards.ieee.org/reading/ieee/interp/ index.html.

Patents

Attention is called to the possibility that implementation of this standard may require use of subject matter covered by patent rights. By publication of this standard, no position is taken with respect to the existence or validity of any patent rights in connection therewith. The IEEE is not responsible for identifying Essential Patent Claims for which a license may be required, for conducting inquiries into the legal validity or scope of Patents Claims or determining whether any licensing terms or conditions provided in connection with submission of a Letter of Assurance, if any, or in any licensing agreements are reasonable or non-discriminatory. Users of this standard are expressly advised that determination of the validity of any patent rights, and the risk of infringement of such rights, is entirely their own responsibility. Further information may be obtained from the IEEE Standards Association.

vCopyright © 2011 IEEE. All rights reserved.

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http://ieeexplore.ieee.org/xpl/standards.jsp

Participants

At the time this recommended practice was published, the Accredited Standards Committee on Electromagnetic Compatibility, C63®, had the following membership:

Daniel Hoolihan, ChairDonald N. Heirman, Vice Chair

Erin Spiewak, Secretary

Organization Represented Name of Representative

Alcatel–Lucent Technologies..................................................................................................................Dheena MoongilanAlliance for Telecommunications Industry Solutions (ATIS)..........................................................................Mel Frerking................................................................................................................................................................. James Turner (Alt.)American Council of Independent Laboratories (ACIL)........................................................................Michael F. Violette............................................................................................................................................................William Stumpf (Alt.)American Radio Relay League (ARRL)......................................................................................................Edward F. Hare..............................................................................................................................................................Dennis Bodson (Alt.)AT&T............................................................................................................................................................George Hirvela...............................................................................................................................................................David Shively (Alt.)Cisco Systems.............................................................................................................................................Werner SchaeferCurtis-Straus LLC..................................................................................................................................................Jon Curtis...........................................................................................................................................................Jonathan Stewart (Alt.)Dell Inc.........................................................................................................................................................Richard WorleyETS-Lindgren.............................................................................................................................................Michael Foegelle..................................................................................................................................................................Zhong Chen (Alt.)Federal Communications Commission (FCC)................................................................................................William HurstFood and Drug Administration (FDA)........................................................................................Jeffrey L. Silberberg (Alt.)Hewlett-Packard................................................................................................................................................John HirvelaInformation Technology Industry Council (ITIC)............................................................................................John Hirvela.........................................................................................................................................................Joshua Rosenberg (Alt.)Institute of Electrical and Electronics Engineers, Inc. (IEEE)...............................................................Donald N. HeirmanIEEE-EMCS.............................................................................................................................................H. Stephen Berger...........................................................................................................................................................Donald Sweeney (Alt.)Motorola.....................................................................................................................................................Joseph Morrissey

viCopyright © 2011 IEEE. All rights reserved.

............................................................................................................................................................. Jag Nadakuduti (Alt.)National Institute of Standards and Technology (NIST)...............................................................................Dennis CamellPolycom.............................................................................................................................................................Jeff Rodman...............................................................................................................................................................Tony Griffiths (Alt.)Research in Motion (RIM)...............................................................................................................................Paul Cardinal................................................................................................................................................................Masud Attayi (Alt.)Samsung Telecommunications.........................................................................................................................Tony Riveria................................................................................................................................................................Kendra Green (Alt.)Society of Automotive Engineers (SAE).......................................................................................................Poul Andersen.................................................................................................................................................................Gary Fenical (Alt.)Sony Ericsson Mobile Communications..........................................................................................................Gerard Hayes.................................................................................................................................................................Steve Coston (Alt.)Telecommuication Certification Body (TCB) Council......................................................................................Arthur Wall...................................................................................................................................................................Bill Stumpf (Alt.)Telecommunications Industry Association (TIA)....................................................................................Stephen WhitesellTUV-America, Inc......................................................................................................................................................[????}Underwriters Laboratories..........................................................................................................................Michael Windler.................................................................................................................................................................Robert Delisi (Alt.)U.S. Department of Defense—Joint Spectrum Center..............................................................................Marcus Shellman............................................................................................................................................................... Joseph Snyder (Alt.)U.S. Department of the Navy—SPAWAR...............................................................................................David SouthworthIndividual Members....................................................................................................................................Daniel Hoolihan........................................................................................................................................................................... John Lichtig..................................................................................................................................................................Ralph M. Showers.................................................................................................................................................................David ZimmermanMembers Emeritus..................................................................................................................................Warren Kesselman........................................................................................................................................................................Herbert Mertel.............................................................................................................................................................H. R. (Bob) Hofmann

At the time this recommended practice was completed, the WG on C63.24 Working Group had the following membership:

H. Stephen Berger, Chair

TBD, Vice-chair

Ed HareHarry HodesDan HoolihanBill Hurst

Dheena MoongilanJeff SilberbergVictor KuczynskiKermit Phipps

Steve WhitesellDavid Zimmerman

viiCopyright © 2011 IEEE. All rights reserved.

ANSI C63.XX-2011Recommended Practice for In-Situ RF Immunity Evaluation of Products, Instrumentation, and Control

Systems in High Reliability Installations

Contents

1. Overview......................................................................................................................................................21.1 Scope.....................................................................................................................................................21.2 Purpose..................................................................................................................................................21.3 Caveats and limitations..........................................................................................................................3

2. Normative references....................................................................................................................................4

3. Definitions, acronyms, and abbreviations....................................................................................................43.1 Definitions.............................................................................................................................................53.2 Acronyms and abbreviations.................................................................................................................5

4. Process Overview.........................................................................................................................................6

5. Preparation for testing..................................................................................................................................85.1 General...................................................................................................................................................85.2 Selection of devices to be tested............................................................................................................95.3 Selection of RF test scan.......................................................................................................................95.4 Selection of the test area......................................................................................................................125.5 Determining ambient environment and incident fields from RF transmitters.....................................13

6. Testing........................................................................................................................................................136.1 Precautions...........................................................................................................................................136.2 Placement of the device.......................................................................................................................136.3 Determination of recommended minimum test distance.....................................................................146.4 Evaluation of device performance – what to look for.........................................................................166.5 Exposing the device to the RF sources................................................................................................17

7. Use of the test results in determining minimum separation distances........................................................21

8. Test report...................................................................................................................................................23

9. Correlation of test results to laboratory immunity testing..........................................................................23

10. Use of test results in EMI policies and procedures..................................................................................23

11. RF test signals and environment...............................................................................................................2611.1 RF modulation...................................................................................................................................2611.2 Field strength.....................................................................................................................................2711.3 Frequency test increments.................................................................................................................2811.4 Physical distance and step size..........................................................................................................2811.5 Cables................................................................................................................................................2911.6 Operating modes................................................................................................................................29

12. Acceptable EUT performance levels........................................................................................................2912.1 Near-end noise...................................................................................................................................2912.2 Far-end noise.....................................................................................................................................2912.3 Operational performance degradation...............................................................................................30

13. EUT monitoring methodology.................................................................................................................3113.1 General guidance...............................................................................................................................3113.2 Telephony devices.............................................................................................................................31

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Systems in High Reliability Installations14. Near-field test procedure..........................................................................................................................33

14.1 Test setup and validation...................................................................................................................3314.2 Test scans and positions....................................................................................................................3414.3 Transmit power..................................................................................................................................3614.4 Test modulation.................................................................................................................................3714.5 RF immunity test procedure..............................................................................................................37

15. Measurement uncertainty.........................................................................................................................38

16. Glossary....................................................................................................................................................38

Annex A (informative) EMC standards and guidelines.................................................................................39

Annex B (informative) Characteristics and types of RF transmitters............................................................40B.1 Characteristics of RF transmitters.......................................................................................................40

Annex C (informative) Alternative RF Test Sources and Test Methods.......................................................47

Annex D (informative) Estimation of incident field strength and minimal test distance without the use of an E-field meter...................................................................................................................................................50

Annex E (informative) Obtaining appropriate experimental licenses............................................................53

Annex F (informative) Recommendations for mitigation of EMI in facilities..............................................57

Annex G (informative) Sample test data sheets.............................................................................................60

Annex H 1 Devices tested.........................................................................................................................61H.1 2 RF TRANSMITTERS USED DURING TESTING..................................................................................62

Annex I (normative) Test equipment specifications......................................................................................70I.1 General.................................................................................................................................................70I.2 Analog phone DC feed circuit..............................................................................................................70I.3 Anechoic or semi-anechoic chamber...................................................................................................71I.4 Antennas...............................................................................................................................................71I.5 Planar dipoles.......................................................................................................................................71I.6 Isotropic field probes............................................................................................................................73I.7 RF signal generator..............................................................................................................................73I.8 Acoustic transmission line...................................................................................................................73

Annex J (normative) Recording waveforms...................................................................................................75J.1 IQ recordings........................................................................................................................................75J.2 Data file structure.................................................................................................................................75

Annex K (informative) Comparison of test methods.....................................................................................77

Annex L (informative) Testing of mobile phone headsets.............................................................................78L.1 Field strength.......................................................................................................................................78

Annex M (informative) RF Immunity—Frequency range and field strength................................................79M.1 Use scenario.......................................................................................................................................79M.2 Frequency range.................................................................................................................................79M.2.1 U.S. cellular system........................................................................................................................79M.2.2 CMRS bands in the U.S..................................................................................................................79M.3 New and emerging services...............................................................................................................81

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Systems in High Reliability InstallationsM.4 Field strength......................................................................................................................................81

Annex N (informative) RF Immunity—Modulation characteristics..............................................................83N.1 Modulation characteristics of radio services......................................................................................83N.2 Amplitude modulation........................................................................................................................84N.3 Pulsed amplitude modulation.............................................................................................................85

Annex O (informative) Bibliography.............................................................................................................86

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Recommended Practice for

In-Situ RF Immunity Evaluation of Products,Instrumentation, and Control Systems in High

Reliability Installations

IMPORTANT NOTICE: This standard is not intended to assure safety, security, health, or environmental protection in all circumstances. Implementers of the standard are responsible for determining appropriate safety, security, environmental, and health practices or regulatory requirements.

This IEEE document is made available for use subject to important notices and legal disclaimers. These notices and disclaimers appear in all publications containing this document and may be found under the heading “Important Notice” or “Important Notices and Disclaimers Concerning IEEE Documents.” They can also be obtained on request from IEEE or viewed at http://standards.ieee.org/IPR/disclaimers.html.

1. Overview

1.1 Scope

This recommended practice provides an in-situ EMC immunity qualification test for products, instrumentation, and control systems in their installed environment. It focuses on systems that require a very high degree of reliability over their operational life.

1.2 Purpose

There is a need to evaluate the in-situ RF immunity of products, instrumentation and control systems in large installations. The standard focuses on installation environments that require a high level of confidence that these products and systems provide required levels of RF immunity. This recommended practice provides a generic method for evaluating the RF immunity of electronic products, instrumentation, and systems, as and where installed or operated. A particular focus is on immunity to RF sources that may enter the environment, intentionally or unintentionally, or be integrated into the operating environment. The characteristics of RF sources in the environment were used to establish the levels and test methods.

In-situ testing is necessary to verify that the required level of immunity is in fact present in an installed system. A number of factors can result in the failure of installed systems to provide the level of electromagnetic (EM) immunity required of them. All systems will have some manufacturing variance from the sample of the product type tested for compliance. In-situ testing validates that the manufacturing variance is within acceptable tolerances. Another factor is that a variation or defect in an installation may

xi of 97Copyright © 2012 IEEE. All rights reserved.

http://standards.ieee.org/IPR/disclaimers.html


Systems in High Reliability Installationscompromise the immunity of the system. In-situ testing is intended to identify any such defects, so that they can be remedied and the required level of immunity protect be provided.

System aging is another reason for in-situ testing. A number of aging mechanisms can degrade a system’s immunity over its operational life. Periodic in-situ testing can help verify that the required level of immunity continues to be in place over the entire operating life of a system.

The test protocol is designed to be performed:

a) in a way that is relatively rapid and practical;

b) to identify specific effects and thresholds (i.e., transmit power and distance) that influence the test results;

c) to generate test results that can be used in the formulation of policies and procedures for managing the electromagnetic environment within a facility.

A preferred method and several alternative RF sources and methods for in-situ testing are outlined in this recommended practice to allow flexibility with regard to the time, personnel, and resources available to perform the testing. These different options provide varying levels of accuracy and comprehensiveness. The most appropriate in-situ test strategy will depend upon the needs and resources of the user of this recommended practice. This recommended practice also provides guidance for selection of the devices to be tested, operation of transmitters used as RF test sources, and assessment of test results.

An important function of this recommended practice is to define a consistent test protocol to allow results to be obtained and compared within and across institutions. To facilitate comparison between organizations, it is important that the recommendations herein are followed, deviations are kept to a minimum, and the testing is performed as consistently as possible.

Policies and procedures for mitigation of electromagnetic interference (EMI), including use or restriction of specific RF transmitters within specific areas, should be based on objective information, including that obtained by the use of this test method. With regard to purchase evaluation, confirming that devices conform to EMC standards through laboratory type testing can provide some information. This recommended practice can be used to supplement that information with evaluation of the actual installed equipment.

1.3 Caveats and limitations

This test procedure is NOT intended to provide precise information on the exact threshold for EMI effects, but instead to offer a basic test that can help identify extremely vulnerable equipment or RF signal combinations so they can be managed appropriately. It is also not intended to substitute for rigorous laboratory electromagnetic compatibility (EMC) testing. This in-situ test cannot control a number of variables. Performing the in-situ test does NOT in any way offer a guarantee against interference risks, but can assist in identifying devices that are particularly vulnerable to the RF signal under evaluation.

The variability of this in-situ test can be minimized by using reference checks, such as an E-field meter to more accurately determine incident E-field strength. While variables cannot be control in-situ as they would be in a laboratory, controlling the test variables as much as possible is vital to the quality of the testing. Sources of uncertainty include:

a) variance in the RF output characteristics of the RF signal generator, amplifier and other equipment in the chain;

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Systems in High Reliability Installationsb) variance in the RF transmission protocol and characteristics due to automatic variation in

response to local operating conditions, such as network loading and network management protocols;

c) the specific type of antenna and small changes in orientation with respect to the device;

d) ambient RF fields;

e) reflection and absorption of RF energy by people, objects, and structures in the test area; and

f) small changes in cable placement and the relative position of the RF test source and the device.

Test results for each device apply only to that specific device and to the frequency, modulation, and field strength characteristics of the RF test transmitter source. The device might be either susceptible or immune to other frequencies, modulations, and field strengths. Results for the same device can vary in the short term due to variability in the test method, movement of people, equipment, or objects in the test area, or variations in local ambient RF fields. The results can also vary over time as the device ages or undergoes service or maintenance. Results for different units of the same model can vary for these same reasons, as well as differences in design or manufacture (e.g., design revisions, component substitutions, tolerances, physical location of components and wires, assembly).

2. Normative references

The following referenced documents are indispensable for the application of this standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.

ANSI C63.14-2006, American National Standard Dictionary for Electromagnetic Compatibility (EMC), Electromagnetic Pulse (EMP), and Electrostatic Discharge (ESD) (Dictionary of EMC/EMP/ESD Terms and Definitions).

JCGM 100:2008, Evaluation of measurement data — Guide to the expression of uncertainty in measurementa

JCGM 101:2008, Evaluation of measurement data – Supplement 1 to the "Guide to the expression of uncertainty in measurement" – Propagation of distributions using a Monte Carlo method

JCGM 102:2011, Evaluation of measurement data – Supplement 2 to the "Guide to the expression of uncertainty in measurement" – Extension to any number of output quantities

JCGM 104:2009, Evaluation of measurement data – An introduction to the "Guide to the expression of uncertainty in measurement" and related documents

IEEE Std 1309™-2005, IEEE Standard Method for the Calibration of Electromagnetic Field Sensors and Field Probes, Excluding Antennas, from 9 kHz to 40 GHz.

3. Definitions, acronyms, and abbreviations

a Available at:http://www.bipm.org/en/publications/guides/gum.html

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Systems in High Reliability InstallationsFor the purposes of this recommended practice, the following terms and definitions apply. The Authoritative Dictionary of IEEE Standards Terms, [O2]a and ANSI C63.14-1998b should be referenced for terms not defined in this clause.

3.1 Definitions

The ANSI C63.14-20068 and The Authoritative Dictionary of IEEE Standards Terms [O2] definitions apply throughout this document, unless otherwise noted below. The definitions contained in this subclause take precedence if duplicate definitions are available.

3.1.1 far-end: The receiving terminal of a communications channel.

3.1.2 near-end: The energized terminal of a communications channel.

3.2 Acronyms and abbreviations

AM amplitude modulation

ANSI American National Standards Institute

AWS Advanced Wireless Services

CDMA code division multiple access

CFR Code of Federal Regulations

CODEC Coder-Decoder

CW Carrier Wave

dB decibel

EMC electromagnetic compatibility

EMI electromagnetic interference

EUT equipment under test

FCC Federal Communications Commission

GSM Global System for Mobile

GTEM Gigahertz transverse electromagnetic

I&C Instrumentation and control

iDEN®c, d Integrated Digital Enhanced Network

IEC International Electrotechnical Commission

a The numbers in brackets correspond to those of the bibliography in Annex O.b Information on references can be found in Clause 2.

c The following information is given for the convenience of users of this standard and does not constitute an endorsement by the IEEE of these products.

d iDEN is a registered trademark of Motorola, Incorporated.

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Systems in High Reliability InstallationsIEEE Institute of Electrical and Electronics Engineers

IQ in-phase and quadrature

P transmitter power (Watts)

PCS personal communications services

PDA personal digital assistant

QAM quadrature amplitude modulation

RETP receive electrical test point

RF radio frequency

SETP send electrical test point

TDMA time division multiple access

TEM transverse electromagnetic

TOE target of evaluation

TX transmitter

UMTS universal mobile telecommunications system

VSWR voltage standing wave ratio

WCDMA wideband code division multiple access

WiFi wireless fidelity

4. Process Overview

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Figure 1 – Test process overview

Preparation for test

o Select device(s)

o Select RF test transmitter source waveforms & levels

o Select test area

o Characterize ambient field levels

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Testing

o Place the device

o Determine recommended minimum test distance

o Expose device with the RF transmitter test source(s)

o Observe device operation

Test results

o Use of test results in determining minimum separation distances

o Test report

o Correlation to laboratory immunity testing

o Use of test results in EMI policies and procedures

5. Preparation for testing

5.1 General

Preparation for in-situ testing involves selection of the frequency band, test frequencies, RF waveforms, and RF power levels to be evaluated. In addition, the test area must be selected or prepared for testing. An important consideration is that the target of evaluation (TOE)a must be prepared, but also other equipment in the area must be safeguarded, so as not to be influenced by the test.

In-situ testing should be considered for new installations as well as for existing equipment and for pre-purchase evaluation. If pre-purchase evaluation is not possible or practical, testing of new electronic devices immediately following purchase should be considered. This evaluation may be done in a staging area, other than the final installation site. However, when feasible the testing should be either performed or repeated in the final installation location. This is particularly true when the characteristics of the installation, such as many cables running considerable distances, may significantly impact the actual RF

a The term target of evaluation is used instead of the commonly used device under test (DUT) or equipment under test (EUT) to allow more flexibility in the use of the test. The TOE may be a single device, a complex and distributed system or a particular function or set of functions. The term TOE is selected to emphasize that the purpose of the evaluation is the focus. The TOE may only be a small but important subset of all the functions a system is capable of. Once identified the challenge is how to monitor the TOE to insure that if there is operational interference it will be identified.

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Systems in High Reliability Installationsimmunity of the system and change the level of immunity present in the installed configuration from that present at other testing.

5.2 Selection of the target of evaluation (TOE)

Judgment should be used in selecting devices or systems for electromagnetic immunity testing. Selecting too many devices will result in lengthy and expensive testing. In some cases the cost of testing may outweigh the potential benefits. However, with prudent selection the value of confirming that safety related and critical systems are providing the necessary level of RF immunity protection will far outweigh the cost.

The following factors should be considered in selecting devices or systems for evaluation:

a) If the TOE is safety related.

b) If the TOE is critical (i.e., used to monitor critical functions, controls a basic process);

c) If the TOE has not been tested for compliance with applicable EMC standards;

d) If failure or malfunction of the TOE could adversely affect the facility or operation;

e) If there are known EMC problems with similar devices due to insufficient RF immunity;

f) If RF transmitters are frequently used in the vicinity of the TOE;

g) If the TOE uses sensitive components or circuitry (e.g., circuits with high-gain amplifiers, sensitive lead wires and cables, and microprocessors can be particularly sensitive);

h) If the TOE has been noted to perform erratically; and

i) If the TOE is repeatedly referred for service, yet when the performance of the TOE is tested, no problem is found, particularly when tested in a service location elsewhere in the building (e.g., the basement) or off-site.

5.3 Failure characteristics

Different functions will be sensitive to differing characteristics of an RF signal. For example hearing aids, telephones and other devices that are used to deliver voice will typically be most sensitive to RF signals with significant amplitude variation that demodulates into the audio frequency band. RF signals that have a constant amplitude or which change amplitude above or below the audio frequency band can miss a sensitivity because they do not produce audio interference. Other functions may require that the RF energy continue for a period of time to produce a failure response. It is important to understand the failure response so that test signals can be used which will maximize the probability of detecting a weakness, should one exist.

The failure characteristics of the TOE should be used in selecting the RF signals to be used. Where there are several differing sets of failure modes or the characteristics of the failure modes are unknown a wider variation in the test waveform may be necessary to insure that there is a high probability that a weakness will be detected by the testing.

5.4 Selection of RF test scan

The RF test scan specifies the frequency band to be covered, the sub-bands and waveforms to be used in each segment of the band and the RF power for each waveform. In addition the number of test points must be selected, to optimize the balance between test time and confidence of the final test results.

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Systems in High Reliability Installations5.4.1 Selection of the frequency range

The frequency range to be tested is typically specified on the low end by a combination of the frequency below which conducted immunity testing is used and below which the TOE is unlikely to be exposed to strong EM fields. The high end of the range is selected by a combination of the frequency above which radiating devices are unlikely to be brought into close proximity with the TOE and where distance and architectural shielding are likely to provide adequate protection.

The frequency band for this standard shall be 1.8 MHz to 6 GHz.b This frequency range may be modified by the specifying authority. If the range is modified that shall be identified in the test report.

5.4.2 Selection of bands and Waveforms

This sub-clause specifies the bands, waveforms and test frequencies required to claim compliance with this standard. Table 2 lists the bands and waveforms in each band to be used when tested using the procedures of this standard. Table 3 lists the minimum test frequencies that shall be tested.

Higher levels of protection are required in the frequency bands allocated for mobile device transmission, which is the reason for the requirements of this sub-clause.c Field experience or knowledge of particular issues in a specific type of environment may lead to applying additional requirements to assure adequate RF immunity in other bands.

The RF level is based on the CW signal before modulation is applied. After the proper RF exposure level is determined, the required modulation is applied for the test.

Table 1 - Test modulation and field strengthd

Frequency range(MHz)

Test waveform(s)a

RF power(W)

Target field strength

(V/m)

Test Distance

400 MHz (LMR)

698-806(700 MHz Cellular)

LTE 0.2e ??

824–849(Cellular Band)

GSM 2 30

902-928(ISM Band)

GSM 2 30

1710-1755Advanced Wireless

LTE 1

b The lower frequency of 1.8 MHz is the top of the AM broadcast band. Above this frequency there are Amateur Radio Service bands, the Citizen Radio band and FCC Part 18, ISM (Industrial, Scientific and Medical) devices operating in several ISM bands, as examples. Note that the Amateur Radio Service bands are often used in an emergency operations center, which may be included in some facilities. The upper frequency is set to include the 5.8 GHz ISM band, which is used for wireless LAN’s and a variety of other services.

c For the portion of the mobile phone bands allocated for use in the U.S. for the handset transmit channels an immunity of 30 V/m is recommended. For other bands, an immunity of 10 V/m is recommended, which is consistent with the IEC recommended immunity level for industrial equipment.

d The rows in the table identify the frequency bands of most interest. These bands historically have had the highest number of reported interference problems in field experience.

e See 3GPP TS 36.101 V9.9.0 (2011-09) Sections 6.2.2, 6.6.2, and 6.6.2.2.3 and Table 6.6.2.2.3-1, which specifies the spectrum emission limits for available channel bandwidths. UE in this band operate as class 3 devices under the 3GPP standard.

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Services |(AWS)

1850–1915(PCS Band)

GSM 1 30

2155-2175Advanced Wireless

Services |(AWS)

2

2400-2483.5(ISM Band)

2500-2689(Mobile)

WiMAX 2

3650-3700(Land Mobile)

WiMAX 1W/25MHz

eirp

4940-4990(Land Mobile)

2

5725-5875(ISM Band)

aThe modulation scheme used shall be recorded and justified in the test report.

Table 2 – Standard test frequencies

StepFrequency

[MHz]Frequency

[MHz]1 824.00 1850.002 832.24 1868.503 840.56 1887.194 848.97 1906.065 N/A 1915.00

Three categories creating the test modulation are allowed:

Recreated modulation of transmitting devices

Abstracted modulations, using the salient characteristics of transmitting devices

Generalized modulation

The preferred method of this standard is recreated modulation. Recreated modulations are recordings or recreations of an RF transmitter that are fed to an RF generator capable of reproducing the RF transmission. This method is preferred by this standard because, when performed with a bandwidth and sampling rate sufficient to fully capture and recreate the original transmission, it reproduces the fine structure and exact parameters of actual transmitters. They are superior to testing with actual transmitters because although they are derived from the signals of actual transmitters, they can be reproduced more repeatedly and under controlled conditions. Such modulations are often obtained by using a RF vector signal analyzer to record

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Systems in High Reliability Installationsthe signals of actual transmitting devices.f The signal is usually saved as an In-phase and Quadrature (IQ) file that can then be reproduced by a RF vector signal generator. The files of recorded transmissions may be shared between laboratories in order to assure lab-to-lab signal modulation repeatability of tests. Annex J provides further guidance on recording and data file structures.

Recorded waveforms also have possible limitations. If the recorded waveform does not encapsulate changes in EUT behavior, like output power adjustments, or other changes like those discussed in the previous paragraph, then the test will be incomplete and not truly realistic. Further, the fidelity of the recording and playback must be sufficient to recreate the salient features of the transmission. If the recording or recreation lacks adequate fidelity, then the test may be deficient.

An abstracted modulation of a Global System for Mobile (GSM) signal might be a simple pulse modulation of 217 Hz and 1/8 duty cycle. Abstracted modulations at times are more easily created. However, their effectiveness is dependent upon having a correct understanding of the critical parameters of the actual transmitted signal. If the critical parameters are not captured, then the test results may not predict well the actual field performance of a product. It is not permissible to use this method for the purposes of this test standard.

5.5 Selection of the test area

The test area should be selected so as to maximize the effectiveness of the test. Ideally the TOE will be testing in its actual location where it will be installed. If this is not feasible then the test location should come as close as possible to recreating the installation location.

The test area should allow for access to all areas of the TOE to be exposed to the RF.

The potential for interference with other equipment in the area must be carefully considered. Steps must be taken to either perform the test at a time when other systems can be powered down or otherwise safeguarded from the possibility of being adversely affected.

If the test area will not the actual installation location, then the area in which in-situ testing is to be performed should be located away from critical areas. It should be selected such that there are no critical devices in use in adjacent rooms or on the floors above and below that would be adversely affected by the test. During the test, no other RF transmitters should be operating in the test room or in adjacent rooms or on the floors above or below that could affect the testing. See 5.1 for precautions regarding electronic devices in use in nearby areas.

The test should be performed in an area that is as free as possible of structures and metallic objects. Approximately 6 m x 6 m of clear area is recommended. Ideally there should be at least 1.5 m between the device (including its cables) and the nearest wall or structure, as well as sufficient available room to back away from the device if an interaction is observed. If the available test area is smaller than these recommendations, the test setup can be moved or rotated as described in 5.6. If there are metal blinds on the windows, they should be fully raised (opened) during the test. This is because prior testing has found that metal blinds can act as a phased array and have a tuning effect that can distort the RF field pattern in the test room. The basement of a facility is often a good location for the test area because it can offer significant attenuation of the outside RF signals entering the test area (i.e., provide a quieter ambient RF environment for the test) and can likewise attenuate the RF signals generated by the in-situ test transmitters exiting the test area (i.e., reducing likelihood of interference with licensed networks). In addition, basement rooms are often remote from critical areas.

Staff members not participating in the test, and visitors should be excluded from the test area during testing.

f When recording transmissions a capture bandwidth shall be used that is greater than the 6 dB bandwidth of the transmission. The sampling rate shall meet the Nyquist criteria for the fastest variation in the transmission.

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5.6 Determining ambient environment and incident fields from RF transmitters

In the preferred test procedure, use of an E-field meter is recommended for measuring the ambient field levels from external RF sources, determining the minimum test distance, and measuring the E-field level from the RF transmitter at any distance at which EMI events are observed with the device under test. E-field meters and probes used should have a minimum frequency range of detection of < 100 MHz to > 2 GHz. Probes with ranges that are greater than <100 MHz to > 2 GHz can be used, as long as the probes are calibrated to operate in the ranges in which the RF transmitters will be operating. Probes that have a range up to only 1 GHz can be used for mobile phones that transmit signals in the 824-848 MHz band, as well as for radio technologies that transmit below 1 GHz. Probes should be isotropic, and the meter should have a sensitivity of at least 30 dB below the typical power of mobile phones and radios in the near field, or a sensitivity < 1 V/m. If the cost of purchasing an E-field meter and probes is prohibitive, it might be possible to rent the equipment or to pool resources with another organization. Even with the use of an E field meter, however, some uncertainty can be introduced due to non-uniform response times of different probes and their ability to capture all the energy in complex modulated signals.

If an E-field meter is not available, the incident field strength from fixed transmitters and dynamically controlled transmitters placed in a test mode with known output power levels can be estimated as a function of separation distance. The incident field strength at a given distance can be approximated from the information provided in Annex D.

6. Testing

6.1 Precautions

As noted in 5.5, this in-situ test could affect devices in use in rooms in the vicinity of the test area, including rooms on the floors above and below. For this reason, unless the test area is well-shielded, it should be far from areas where critical systems are actively being used. The in-situ test should be performed with caution. Personnel that are responsible for operations in the test area that might be affected should be informed in advance when and where the testing will take place. Unless prior in-situ testing has shown all electronic devices in use in nearby areas to be immune to the RF transmitters that will be used during the in-situ test, the professionals should be alerted that the testing could cause these devices to malfunction and that they should maintain heightened vigilance during the test. The professionals should then be notified prior to the beginning of the test and again when testing is completed. If the testing is found to cause a device in use in a nearby area to malfunction in a way that could have adverse consequences, testing should cease immediately and the test should be moved to another location and/or time. Alternatively, the affected device could be substituted with one that has been found to be immune to that particular RF transmitter at that separation distance. Devices that are in use in nearby areas and are found to malfunction during this in-situ test should themselves be referred for in-situ testing.

6.2 Placement of the device

If the available test location permits, place the device to be tested and its cables in the center of the cleared area as shown in Figure 1, with the cables extended to the rear of the device. If a test area of minimum dimensions 6 m x 6 m (20 ft x 20 ft) is not available, set up the device subject to the constraints of the available test area. As specified in 5.6.1, it might be necessary to rotate the test setup within the available area during the test.

Cables that exit the front or top of the device should be routed over the top and to the rear. If the device has one or more sensors and/or connections, place them approximately 80 cm (31 in) off the floor or ground,

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Systems in High Reliability Installationsand approximately even with the front panel or surface of the device near the front of the device as shown in Figure 1, with the cables extended to the rear of the device as far as possible, up to a length of 3 m (10 ft) and with cables for sensors doubled over as shown in Figure 1. For cables longer than 3 m (10 ft) that do not include a coupling point, stretch out the first 3 m (10 ft) to the rear of the device and bundle the remainder noninductively (i.e., in a serpentine, or “S”-shaped bundle). For cables less than 3 m (10 ft) in length that do not include a coupling point, stretch them to their full length as much as possible. Stretch coiled cables as much as practical without causing damage. If necessary, use blocks of wood to hold cables in place.

If the device is normally used on a table, place it on a nonconductive (e.g., wooden) table approximately 80 cm (31 in) high. If the device is floor-standing, position it on the floor or ground. For devices that normally incorporate a stand, it is appropriate to include the stand in testing, as that would be the normal use case. Support any cables approximately 40 cm (16 in) off the floor or ground using nonconductive objects (e.g., wooden or nonconductive plastic chairs or wastebaskets). The transition of the cable from the height of the device to a height of 40 cm (16 in) should be over as short a distance as possible. If simulators are used to provide signals to the sensors and/or connections, care must be taken to ensure that they are not affected by the RF transmitter and that they do not conduct RF energy into the device. The preferred method for avoiding the conduction of additional RF energy into the device is to use nonconductive means such as fiber optics to couple the simulated signals to the vicinity of the device sensors. If this type of coupling is not available, small, shielded, battery-operated simulators are recommended. If simulators are found to be affected by the RF transmitters used, the test should be performed with the simulators located away from the test area, unless the method used to couple the simulator signals to the device sensors (e.g., cables) is found to affect the test results. If simulators must be close to the sensors, they should be supported at a height of approximately 80 cm (31 in) and placed behind the sensors, as shown in Figure 1. If the simulator is found to affect the test results, it can be placed under a shielded enclosure or wrapped completely in aluminum foil.

Any details of the test setup not specified herein should be as close as possible to actual use conditions.

6.3 Determination of recommended minimum test distance

This section specifies how to determine the recommended minimum test distance for each transmitter.

CAUTION—To prevent possible damage to the device under test and possible malfunction of devices used in nearby critical areas, do not perform in-situ testing with output power greater than 8 W.

6.3.1 Determining minimum test distance using an E-field meter

To determine a starting distance of ~ 20 V/m using an E-field meter, place the E-field probe next to (or on) the device under test. (Note: The symbol “~” means approximately.) For each transmitter, set the transmitter to maximum power. Because handsets are designed to operate when loaded with a human hand, it is acceptable to hold the transmitter while measuring the field strength as well as during the actual testing. Although the radiating pattern will not be completely isotropic, most 824-848 MHz mobile phone transmitters and radios are not designed with a directional radiating pattern. While the radiation pattern can be affected by the presence of the hand, and is more complex with 1850 – 1909 MHz mobile phone transmitters due to multiple field polarizations, it is acceptable and generally represents the normal use case if the back of the RF transmitter is positioned facing the E-field probe while holding the transmitter in your hand to determine and record the distance at which 20 V/m is achieved. The distance at which 20 V/m is achieved is the recommended minimum test distance. Beginning at the 20 V/m distance, back away from the E-field probe to assure that the field strength decreases with distance. Although the 20 V/m value can be an under-estimation for pulse-modulated signals (e.g., GSM mobile phones) due to the slower response time associated with many E-field meters, this approximation should be sufficient to obtain a relative measure as well as offer protection to the device.

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Systems in High Reliability Installations6.3.2 Determining minimum test distance without the use of an E-field meter

If the test is performed without an E-field meter, Table 3 can be used to determine the recommended minimum test distance for an RF transmitter with a known output power.

Table 3 – Test distancesTransmitter output power Recommended minimum test

distanceTest distance that achieves

3 V/m to 7 V/m 0 < P 600 mW 0.25 m (10 in) 1 m (39 in) 600 mW < P < 2 W 0.5 m (20 in) 2 m (79 in)2 W P 8 W 1 m (39 in) 3 m (118 in)

6.3.3 Frequency test increments

The frequency range shall be tested with frequency steps no larger than 10% of the lower frequency of each frequency step for the coarse scan and 1% for the final scan. Stated a different way, assuming a test is performed starting at the lowest frequency and ascending in frequency, the next frequency step shall be 10% of the current frequency for coarse scans and 1% for final scans. The EUT shall be exposed at each frequency step for a time long enough to incorporate the operating cycle of the EUT.

6.3.4 Physical distance and step size

A set of planes shall be defined, 25.0 mm ±2 mm distance from the leading point of each face of a device. The intended faces to be tested are the top of the EUT and each side. It is not intended to require testing of the bottom of the product. A scan shall be performed on each face for two orthogonal polarizations of the antenna.

The scan of each face shall use geometric step sizes of 25% of the shortest wavelength of the band being scanned or smaller. For the coarse scan, steps of 50% of the shortest wavelength of the band may be used (see Figure A-4). In this paragraph, band means the frequency range being tested at each tuned dipole position. For example, if a test is run using two scans, one using a dipole to test from 824–849 MHz and a second scan using a different dipole to test to 1850–1915 MHz, then two different step sizes may be used. The step size for the scan that sweeps each location from 824–849 MHz shall be ≤ 8.8 cm, 25% of the wavelength of 849 MHz, and the step size for the scan from 1850–1915 MHz shall be ≤ 3.9 cm, 25% of the wavelength of 1915 MHz.

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Figure 2—Physical scanning step sizes

6.3.5 Cables

One scan shall include a length of each cable from the EUT to a distance of one half of a wavelength, for the lowest frequency in the band being scanned, with the radiating elements of the illuminating antenna oriented in parallel with the cable to maximize coupling. This is the only polarization required when scanning cables, and the requirement for two polarizations found in 11.4 does not apply. Testing with the antenna cross polarized to the cable will result in less coupling to the cable and therefore is not required.

6.4 Evaluation of device performance – what to look for

With the RF transmitter off, establish and verify normal operation of the device. During the in-situ RF immunity test, observe any abnormal operation. (See the list of suggested response descriptions below). After the RF immunity test is completed, verify that the device operates normally and was not damaged during the test.

During the in-situ RF immunity test, record the responses of the device as a function of the RF transmitter distance, orientation, and frequency. The list below is suggested as a guide in noting device performance degradation that might occur as a result of the test. However, device-specific descriptions of any deviations from normal performance should be recorded.

a) No change in operationb) Cessation of function without visible and/or audible alarmc) Cessation of function with visible and/or audible alarmd) Change in function or delivered therapy with alarm

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Systems in High Reliability Installationse) Change in function or delivered therapy without alarmf) Reboot or power down with loss of datag) Reboot or power down without loss of datah) Manual reset required to continue operationi) Change in mode or operational state without alarmj) Change in mode or operational state with alarmk) Alarm malfunction or failure to alarml) Visible and/or audible alarm with continuation of functionm) Change in measured and/or displayed data with change in operationn) Change in measured and/or displayed data without change in operationo) Change in audio indicatorp) Distortion of displayed waveformsq) Display malfunctionr) Recorder malfunctions) Error message or service codet) Other (describe)

When noting the response of the device to the RF transmitter, it is also important to distinguish between effects that would and effects that would not impact plant or operator safety or the monitoring and/or control of plant operations. Noise that is readily recognizable as artifact would be unlikely to affect the monitoring and/or control of plant operations, and could be considered acceptable. However, organizations should evaluate the response of each device tested to determine if it is acceptable or unacceptable.

6.5 Exposing the device to the RF sources

While one person observes the performance of the device, another person should operate the transmitter. There should be no humans, structures or objects between the transmitter and the device. For consistency, the person observing the device should remain in the same location and position during the test.

During the test, operate the device in the mode that is most critical. If the device has several such modes, operate it in the mode(s) that is/are considered to be the most sensitive to RF disturbances. Exploratory testing may be required to determine the mode that is most sensitive to RF disturbance.

6.5.1 Preferred procedure: area testing using an E-field meter

In the preferred test procedure, the device under test is set up in a test area as specified in 4.4 and an E-field meter is used to measure the RF ambients and the field strength to which the device under test is exposed during the test.

With the device and all RF transmitters to be used as test sources turned off, measure the strength of the ambient RF fields with the E-field meter. Record the measured value, noting the date, time, and location. The RF ambient can change over time, so measure it before testing with each transmitter and after testing is completed, recording the measured values and the time that the measurement was performed.

Turn on a test transmitter and operate it according to 0 at a distance from the device under test as determined in 5.3.1 (i.e., the recommended minimum test distance). Use the E-field meter to confirm that the transmitter is transmitting at the same power as in the determination in 5.3.1, i.e., producing approximately 20 V/m at the recommended minimum test distance. If not, adjust the minimum test distance accordingly. Move the transmitter slowly around all sides, the top, and along the cables of the device,

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Systems in High Reliability Installationsmaintaining the recommended minimum test distance from the device and its cables, sensors, and electrical accessories. Be sure to include exposure to openings, seams, and display windows. Note that some device functions respond slowly to RF disturbances. For example, if the RF affects a parameter that is time-averaged by the device, it might take 10 s or more before the full effect of the test transmitter is apparent.

Observe any degradation in the performance of the device. If performance degradation occurs, release the transmitter talk button or turn the transmitter off to see if the performance degradation ceases. Then re-key or turn on the transmitter to see if the performance degradation recurs.

If simulators are used and there is a question as to whether an observed effect is due to the susceptibility of the simulator or of the device under test, the following approach should be taken:

• Move the simulator away from the transmitter;

• Place the simulator under a metal trash can; or

• Wrap the simulator completely in aluminum foil.

If any of the above causes the performance degradation to cease, it could be due to a susceptibility of the simulator. Repeat the test with the simulator in the configuration that was found to cause the performance degradation of the simulator to cease.

If reproducible performance degradation of the device under test is found, position the transmitter in the location found to cause the greatest effect and move the transmitter away radially from the device and/or its cables, sensors, and electrical accessories until the performance degradation ceases. Record the effect on the device and the distance. If this effect is determined to be unacceptable, the distance at which the interference ceases is the approximate minimum separation distance for the device (including cables, sensors, and electrical accessories) and the particular transmitter tested. If the test is performed indoors and the interference does not cease within the test area, proceed out a door with the transmitter until the interference ceases and note the distance, as well as the details of the intervening architecture. If necessary, rotate the test setup to permit backing away sufficiently in this direction.

If the transmitter does not affect the device, or if there are effects but they are determined to be acceptable, then the minimum recommended separation distance between that transmitter and that device is the minimum recommended test distance.

If, for a given transmitter and device, no performance degradation occurs, record this fact.

If it is not practical to alternate the antenna orientation between vertical and horizontal as described in 0, perform the test first with the transmitter so that the antenna is vertical (if practical), parallel to the nearest side of the device, then again with the antenna horizontal (if practical), perpendicular to the nearest side of the device.

6.5.2 Alternative procedure 1: area testing without E-field meter

Proceed as in 5.6.1, but without E-field measurements and beginning at the recommended minimum test distance determined in 5.3.2.

6.5.3 Alternative procedures 2 and 3: in-situ testing

In some cases when it is impractical to relocate the device to an appropriate test area as described in 4.4, or in cases where the performance in the actual use environment is desired, testing can be performed at the normal use location of the device (i.e., in situ). Because space might be limited when performing in situ testing, it might not be possible to achieve minimum separation distances at all points around the device,

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Systems in High Reliability Installationsand in such cases a combination of close-in testing as described in 5.6.4 might need to be implemented. Because of the more complex environment in situ, the nature of the field when in close proximity, and the effects of absorption and reflection, the results are likely to be more variable. This can result in more variable results from location to location within a facility (even within the same room), and from facility to facility, than the preferred test method in 5.6.1.

If any close-in testing (per 5.6.4) is to be performed during in-situ testing, it should be done with caution and with responsibility for any damage or malfunction to the devices being assumed by the test group. The in-situ test could also affect electronic devices in use in nearby rooms, as well as on the floors above and below the in-situ test area. See 4.4 and 5.1 for precautions regarding electronic devices in use in nearby areas.

6.5.3.1 Alternative procedure 2: in situ testing with E-field meter

With the device and all RF transmitters to be used as test sources turned off, measure the strength of the ambient RF fields with the E-field meter. Record the measured value, noting the date, time, and location. The RF ambient can change over time, so measure it before testing with each transmitter.

Proceed as in 5.6.1, subject to the constraints of the test location.

6.5.3.2 Alternative procedure 3: in-situ testing without E-field meter

Proceed as in 5.6.1, subject to the constraints of the test location but without E-field measurements and beginning at the recommended minimum test distance determined in 5.3.2.

6.5.4 Optional procedure: close-in testing

For the purpose of this recommended practice, close-in testing is defined as in-situ radiated RF immunity testing in which the transmitter operator brings the transmitter closer than the recommended minimum test distance (e.g., in order to determine how the device might react if transmitter users did not observe separation distance recommendations). In close-in testing, minimum separation distances between RF transmitters and devices can be decreased to as little as a few centimeters (or the transmitters and devices could even be in direct contact), resulting in E-field strengths incident upon the device that significantly exceed 20 V/m. Users of this recommended practice might decide to implement this close-in strategy initially or if it is first shown that at the 20 V/m distance, no effects are observed.

If close-in testing is performed, damage to the device under test could result. Personnel who decide to perform close-in testing must assume responsibility for any damage. It would be prudent to limit close-in testing to transmitters of 2 W and less. As recommended in 5.5, it is essential that normal operation of the device be verified both before and after close-in testing. However, in relevant studies reported in the literature in which testing was performed in very close proximity, there have been no reports of damage or permanent device malfunction. In addition, testing at distances of only a few centimeters might be more representative of the normal use case because individuals using portable RF transmitters in a facility could bring them much closer than 25-50 cm to devices.

Most studies in the literature that used close-in testing did so to drive any effects that might have existed, and then the tester increased distance or decreased transmit power to find the threshold. Very few effects were seen at the recommended minimum test distance of 25-50 cm, with most occurring at distances in immediate proximity or only a few centimeters away.

Close-in testing should be performed in a manner analogous to testing at the minimum recommended test distance, as described in 5.6.1, but beginning with the transmitter in direct contact with the device or 0.25 cm to 1 cm away, as determined by the organization or the personnel who accept responsibility. While an E-field meter could optionally be used to measure ambient fields before and after this test, measurements of

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Systems in High Reliability Installationsfield strengths produced by transmitters very close to the E-field probe (in the near field) would likely be too inaccurate to be meaningful.

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7. Use of the test results in determining minimum separation distances

The test results for each transmitter-device pair consist of whether there was an interaction, the distance at which the interaction ceased, and the effect (if any) of the transmitter on the device.

The test results should be used to determine a minimum separation distance between each tested transmitter and device (including cables, sensors, and electrical accessories). When assessing the test results, it is essential that they be interpreted bearing in mind the caveats and limitations listed in Clause 2. The test results apply only to that specific, individual device. Other units of the same model can behave differently. The test results also apply only to the frequency, modulation, and field strength characteristics of the RF transmitter used. The device can be either susceptible or immune to other frequencies, modulations, and/or field strengths. In addition, the test is affected by the structure of the facility in which the test is performed, as well as by furniture and nearby objects. Results might be different in another location. Multiple reflections of RF fields in the actual use location can sum in such a way that interference can occur at distances greater than the minimum separation distance determined from this test procedure.

The organization should determine whether each effect or performance degradation observed during the test is acceptable (see 5.5). The advice of clinical staff is helpful in determining the clinical acceptability of any observed performance degradation.

For each transmitter and device, the minimum separation distance can be determined as follows (see Figure3):

a) If there were unacceptable changes in device performance during the test, the minimum separation distance is equal to the largest distance at which the performance changes occurred.

b) If testing at the 20 V/m distance threshold was the only test performed and either there were no changes in device performance or the performance changes were acceptable, the minimum separation distance is equal to the recommended minimum test distance (at 20 V/m) for that transmitter.

c) If close-in testing was performed and either there were no changes in device performance or the performance changes were acceptable, it can be assumed that the device is not overly sensitive to the RF emissions. However, it might still be prudent to main¬tain a minimum separation distance of approximately 0.25 m (10 in) due to the variability of this in-situ test method, particularly the field strengths in the near field (a distance of less than several wavelengths of the transmitter carrier frequency), the power level of the transmitter, and the effects of the test location.

Results of the test should be considered in the development of policies and procedures for mitigation of EMI with respect to each device and RF transmitter used in the test (see 9).

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Figure 3 - Determination of minimum separation distance

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8. Test report

The test report should document the test conditions and results in detail, to facilitate reproduction of the test results by others. The documentation should include the model and serial numbers of the equipment used. It should also include photographs and/or diagrams of the test area and the test setup. For each transmitter, it should list the frequency, the minimum test distance, the antenna orientation, the responses of the device (if any), whether the responses were considered acceptable or unacceptable, and the experimentally determined minimum separation distance. See Annex Y for sample test data sheets.

9. Correlation of test results to laboratory immunity testing

Factors that could lead to differences in test results between laboratory and this in-situ test are as follows:

Some laboratory test standards allows manufacturers to claim lower immunity test levels (than 3 V/m or 10 V/m), provided the lower test level can be justified based on significant physical, technological or physiological limitations.

Compliance with EMC standards is usually demonstrated by “type testing”

o usually only one prototype is tested

o production units can vary

o device EMC characteristics can change with design changes, age, and servicing

Differences in the test conditions between laboratory and in-situ testing, which could include differences in device operating mode and differences in the modulation characteristics of the RF test signals.

The acceptability of performance degradation during the laboratory test with some commonly used standards is somewhat open to interpretation. What might have been considered acceptable by the device manufacturer might not be considered acceptable by some organizations.

The device might have been tested to early edition of a standard, which often have somewhat less stringent requirements.

Many manufacturers assure margin between the test level and the actual immunity of the device.

Compliance is based on the most susceptible frequency found and the modulation used during testing. The device might be considerably more immune at other frequencies and modulations.

If desired, the radiated RF immunity of the device can be estimated using Equation (F.1) of Annex F by solving the equation for E, substituting the rated power of the transmitter for P, and substituting the experimentally determined minimum separation distance for d.

10. Use of test results in EMI policies and procedures

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Systems in High Reliability InstallationsThe results of this in-situ test should be considered in setting the organization’s policies and procedures for mitigation of EMI, particularly with respect to the devices and the RF transmitters used in the test.

The organization’s policies and procedures should ensure a separation distance between each RF transmitter and each device (including cables, sensors, and electrical accessories) that is greater than the largest experimentally determined minimum separation distance. Individual organizations can choose to take additional action based on changes in device performance that were observed during the test.

If unacceptable effects on a device resulted from a particular RF transmitter during in-situ testing, the following are actions that organizations should consider:

a) Instituting policies and procedures and educating staff, and visitors to ensure separation of the RF transmitters that caused unacceptable effects from the devices (including cables, sensors, and electrical accessories) that were susceptible. For example, mobile telephone users can be requested to turn their telephones off when in certain areas. Hand-held transceiver users can be asked not to transmit when in certain areas, but only to receive. It would be prudent to restrict the use of an RF transmitter to a distance at least twice that which caused an unacceptable effect in a device. Larger safety margins might be necessary if there are large, electromagnetically reflective surfaces present in the use location. Organizations should be aware that the composition of walls and floors might or might not be such that transmission of RF signals is blocked appreciably. Informative brochures that explain the reasons for transmitter use restrictions should be available to the affected transmitter users. Locations should be identified where transmitters can be used without affecting devices. Alternatively, transmitter users could be provided with alterna¬tive means of communication, such as (wired) pay telephones or house telephones.

b) Relocating sensitive devices (including cables, sensors, and electrical accessories) so that they will be further from areas where particular RF transmitters are commonly used.

c) If the RF transmitter is power-controlled, installing an in-house system to lower the RF output power of the transmitter within the facility.

d) Replacing sensitive devices with devices that are more immune.

e) Using the device in a shielded room. In such a case, RF sources should be prohibited from this room.

NOTE—Unless special RF-absorbing material is installed inside a shielded room, the use of an RF transmitter inside the shielded room can produce field strengths in some areas of the room that are considerably higher than that predicted by free-space calculations [e.g., by using Equation (F.1)]. (See [B12].) Also, transmitters with adjustable output power such as mobile (cellular and PCS) telephones might attempt to transmit at their maxi¬mum power when brought into a shielded room.

f) Sharing the results of in-situ testing with the device manufacturer and the RF transmitter manufacturer or service provider and discussing ways to minimize the potential for EMI.

g) Retaining the services of an EMC professional for assistance in characterizing the electromagnetic environment, solving specific problems, and/or educating staff.

If device performance effects that were noted during the test occur during use of the device, this could indicate possible violations of the organization’s separation distance policies and procedures or inadequate separation distances.

When new communications systems, wireless computer systems, or any new RF transmitter systems are being purchased for the facility, particularly those with different frequencies, modulation techniques, and/or

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Systems in High Reliability Installationsoutput power from transmitters that have already been tested, the organization should consider repeating this in-situ test with the new transmitters, preferably prior to purchase.

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11. RF test signals and environment

When testing to this standard the EUT shall be exposed to RF environments meeting the requirements of this clause.

The preferred method of RF illumination is plane wave exposure performed in an anechoic or semi-anechoic chamber complying with the requirements and following the procedures of IEC 61000-4-3 but as modified by this standard. Alternate procedures are near-field scanning using an illuminating probe or antenna, such as the planar dipole (see I.5) and Gigahertz transverse electromagnetic (GTEM) illumination. If a dispute about test results arises, the test method agreed upon by the disputing parties shall prevail. If no agreement on a test method can be reached the result using a semi-anechoic chamber test shall prevail.

When using the preferred method, illuminate the EUT as defined in IEC 61000-4-3 at 10 V/m then, in the frequency ranges specified in Table 1, with the defined modulation illuminate the EUT with a 30 V/m field.

When using the near-field illumination method, a radiating antenna or probe is moved over a surface 25.0 ±1.0 mma from a plane defined by the surface of the EUT and attached cables, exposing it to the required modulation and field strength. Typically, for reasons of test time, a coarse scan is first performed. The coarse scan uses larger physical step sizes and frequency increments. It may use higher exposure levels to help identify RF sensitive areas. Following the coarse scan, a final scan is performed of sensitive areas identified in the coarse scan. The final scan will use smaller physical steps and frequency increments to correctly assess a product’s RF immunity.

provides the minimum requirements of this standard, which is that a product demonstrates a minimum level of immunity over the entire frequency band specified and enhanced RF immunity in the mobile phone transmit bands. A specifying authority may develop their own profile and require it but using the test methods of this standard. However, a claim of compliance to this standard shall mean a product meets the immunity requirements when stressed using the parameters specified in applied using the IEC 61000-4-3 test method as modified in this document.

11.1 RF modulation

The following four categories of RF test modulation exist:

Recreated modulation of transmitting devices

Actual modulation from transmitting devices

Abstracted modulations, using the salient characteristics of transmitting devices

Generalized modulation

The preferred method of this standard is recreated modulation. Recreated modulations are recordings or recreations of an RF transmitter that are fed to an RF generator capable of reproducing the RF transmission. This method is preferred by this standard because, when performed with a bandwidth and sampling rate sufficient to fully capture and recreate the original transmission, it reproduces the fine structure and exact parameters of actual transmitters. They are superior to testing with actual transmitters because although they are derived from the signals of actual transmitters, they can be reproduced more repeatedly and under controlled conditions. Such modulations are often obtained by using a RF vector signal analyzer to record

a To obtain the required precision a robotic movement mechanism may be required.

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Systems in High Reliability Installationsthe signals of actual transmitting devices.b The signal is usually saved as an In-phase and Quadrature (IQ) file that can then be reproduced by a RF vector signal generator. The files of recorded transmissions may be shared between laboratories in order to assure lab-to-lab signal modulation repeatability of tests. Annex J provides further guidance on recording and data file structures.

Actual transmitting devices could be used to test the RF immunity of products. This, however, has limitations. Many transmitters vary their transmission in ways that the user cannot control. Power management may automatically adjust the RF transmission power without any user intervention or notification. The form of the transmission may vary by the data being transmitted. Also, the transmission may change depending upon the level of speech activity due to discontinuous transmission. Further, it is very difficult for multiple labs to have the same test devices; therefore it is hard for them to perform the same test in a repeatable fashion.

Recorded waveforms also have possible limitations. If the recorded waveform does not encapsulate changes in EUT behavior, like output power adjustments, or other changes like those discussed in the previous paragraph, then the test will be incomplete and not truly realistic. Further, the fidelity of the recording and playback must be sufficient to recreate the salient features of the transmission. If the recording or recreation lacks adequate fidelity, then the test may be deficient.

An abstracted modulation of a Global System for Mobile (GSM) signal might be a simple pulse modulation of 217 Hz and 1/8 duty cycle. Abstracted modulations at times are more easily created. However, their effectiveness is dependent upon having a correct understanding of the critical parameters of the actual transmitted signal. If the critical parameters are not captured, then the test results may not predict well the actual field performance of a product. It is not permissible to use this method for the purposes of this test standard.

Generalized modulations, such as 1 kHz of 80% amplitude modulation (AM), are the traditional method for RF immunity testing. These have been used with the belief that they adequately stressed a product and identified the immunity to a wide variety of RF transmissions. However, some manufacturers have reported that these modulations do not excite all the failure modes of their products. Therefore, this standard calls for the use of real-world waveforms.c

provides a test profile that includes the use of the GSM signal as a test for the cellular bands. In the U.S., the dominant transmission protocols used in the cellular and personal communications services (PCS) bands are GSM and code division multiple access (CDMA). The GSM signal demodulates more energy into the audio band and therefore is far more likely to cause interference than the CDMA signal. Therefore, it was chosen as the test waveform for those bands.

A specifying authority may construct its own profile to this standard by defining the frequency bands, modulations, and field strength to be used during the testing. It may want to obtain recordings of the waveforms to be used and provide those to assure that all laboratories will perform the test using exactly the same test signal.

11.2 Field strength

See Table 6 for field strengths by frequency band.

b When recording transmissions a capture bandwidth shall be used that is greater than the 6 dB bandwidth of the transmission. The sampling rate shall meet the Nyquist criteria for the fastest variation in the transmission.

c Transmissions from actual devices may have varying characteristics. For example, a transmission may be more interfering during ringing than while a call is in progress or other events, such as transitions from idle to active, may have particular characteristics. As these nuances are identified, recorded waveforms may be made that capture the transmission states that are of greatest interest or are most problematic.

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11.3 Frequency test increments

The frequency range shall be tested with frequency steps no larger than 10% of the lower frequency of each frequency step for the coarse scan and 1% for the final scan. Stated a different way, assuming a test is performed starting at the lowest frequency and ascending in frequency, the next frequency step shall be 10% of the current frequency for coarse scans and 1% for final scans. The EUT shall be exposed at each frequency step for a time long enough to incorporate the operating cycle of the EUT.

11.4 Physical distance and step size

A set of planes shall be defined, 25.0 mm ±2 mm distance from the leading point of each face of a device. The intended faces to be tested are the top of the EUT and each side. It is not intended to require testing of the bottom of the product. A scan shall be performed on each face for two orthogonal polarizations of the antenna.

The scan of each face shall use geometric step sizes of 25% of the shortest wavelength of the band being scanned or smaller. For the coarse scan, steps of 50% of the shortest wavelength of the band may be used (see Figure A-4). In this paragraph, band means the frequency range being tested at each tuned dipole position. For example, if a test is run using two scans, one using a dipole to test from 824–849 MHz and a second scan using a different dipole to test to 1850–1915 MHz, then two different step sizes may be used. The step size for the scan that sweeps each location from 824–849 MHz shall be ≤ 8.8 cm, 25% of the wavelength of 849 MHz, and the step size for the scan from 1850–1915 MHz shall be ≤ 3.9 cm, 25% of the wavelength of 1915 MHz.

Figure A-4—Physical scanning step sizes

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11.5 Cables

One scan shall include a length of each cable from the EUT to a distance of one half of a wavelength, for the lowest frequency in the band being scanned, with the radiating elements of the illuminating antenna oriented for maximum coupling with the cable.

When scanning cables, the two polarization requirements of 11.4 do not apply. Testing with the antenna cross polarized to the cable makes little sense and therefore is not required. When testing cables, the antenna is oriented in parallel with the cable to maximize coupling. This is the only polarization required.

11.6 Operating modes

The EUT shall be tested in its most sensitive operating mode. If the most susceptible operating mode is not known and cannot be determined by engineering analysis, then it shall be determined by exploratory testing.

If testing in multiple operating modes is required and the EUT cannot exercise all its data paths or exhibit all its possible failure mechanisms in a single operating mode, the test shall be repeated in as many operating modes as are required to fully evaluate the RF immunity of the EUT. Testing in multiple operating modes is required when it cannot be determined which mode is the most sensitive to RF exposure or where multiple modes may be equally prone to failure. A common example is the need to test in handset, headset, and handsfree mode to fully evaluate the audio paths in a product.

12. Acceptable EUT performance levels

The EUT shall meet the following performance levels during exposure to the required RF levels.

12.1 Near-end noise

If an EUT has a telephone type handset, while in handset mode, the sound pressure level at the handset shall not exceed 40 dB(A).a

If an EUT can have a headset, while in headset mode, the sound pressure level at the headset shall not exceed 40 dB(A).

If the EUT has a speakerphone, the sound pressure level measured 25 cmb in the direction of maximum acoustic output from the speaker shall not exceed 46 dB(A).c This requirement applies whether the EUT is operating in speakerphone mode or not in speakerphone mode. The EUT may be monitored at distances other than 25 cm with corresponding adjustments made in the noise threshold. The threshold for other distances can be determined by transmitting a tone that produces a sound pressure of 46 dB(A) at 25 cm and then measuring the sound pressure at the desired monitoring distance.

12.2 Far-end noisea See the definition for sound pressure level in the glossary in Clause 12 (definition 5).b 25 cm has been selected as the measurement distance for speakerphones to allow testing in smaller RF test chambers, e.g.,

GTEM and mini-reverb chambers. The monitoring distance may be adjusted to be more or less than 25 cm with appropriate adjustment to the required limit.

c The value for speakerphone is determined using an assumption that a typical user will be 50 cm from a speakerphone and expect the same level of performance as when using a handset or headset, less than 40 dB(A) of audible interference.

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Systems in High Reliability InstallationsThe interference at the far end of a voice connection shall not exceed 30 dBrnC.

12.3 Operational performance degradation

The EUT shall not reset, lose data, change LED state, blank or change its display (which makes information unreadable or loses information), disconnect a call, or display any ongoing disruption of its operation during the test.

The EUT may display momentary, self-correcting, transient events during the test.

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13. EUT monitoring methodology

This clause provides guidance on monitoring the EUT during a test to assure that it meets the required performance level.

13.1 General guidance

When planning a test for the EUT, the possible performance degradation mechanisms shall be reviewed and a plan created for detecting if any of the types of performance degradation listed occur during testing. Typically a monitor is provided and checked at each step of the testing process. However, some failure modes, e.g., those that are non-recoverable, may be checked by the test personnel at the end of the test.

13.2 Telephony devices

If the EUT provides telephony service, both the near-end and far-end of the connection shall be monitored during the test.

13.2.1 Near-end monitor

Monitoring of the near-end is accomplished by measuring the sound pressure produced by the receive transducer. Two methods are available for monitoring the near-end noise. In the first method, although the EUT is in the RF chamber, the acoustical measurement must be accomplished outside of the RF test chamber by means of a specially calibrated acoustical measurement setup. The acoustic output of the EUT is conducted to the measurement instrumentation outside the test chamber using a tube or other acoustic transmission channel. In the second method, a RF hardened transducer, e.g., microphone, monitors the acoustic level and transmits its readings to the instrumentation outside of the chamber.

In the first method, with the instrumentation outside the chamber, described below, the telephony device is placed in the operating mode to be tested, i.e., powered in the off-hook condition with the receive transducer active. If the telephony device has a mute function for the operating mode being tested, the mute function may be activated as long as it does not disconnect the microphone and other potentially sensitive circuits and thus obviate the purpose of the test.a The EUT, while muted, shall expose the same potentially sensitive circuits and components to the RF as would be exposed during normal use. So, as one example, it is not acceptable to use a mute function if that function disconnects a microphone from the circuit.

For an analog telephone, a battery feed circuit without a line length simulator is used to power the telephone.

For a digital telephone, a digital connection is made to a reference Coder-Decoder (CODEC).

The acoustical measurement setup delivers the acoustical signal to a measuring microphone outside the RF test chamber. This setup consists of tubing between the point of acoustic pickup and the measuring microphone. The acoustic transmission line “tubing” shall follow the guidance of I.8. The tubing is tightly acoustically coupled to the measuring microphone. When the mode being tested is the handset mode, the point of acoustic pickup is at the receiver of the handset. The tubing is tightly acoustically coupled to the handset receiver. When the mode being tested is the speaker mode, the point of acoustic pickup is 25 cm from the speaker.

a The purpose of allowing a mute function is to eliminate pollution of the test results by environmental acoustic noise.

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Systems in High Reliability Installations13.2.1.1 Monitor normalization

The acoustical measurement setup for either method shall be normalized as follows.

The EUT handset receive frequency response and the speaker receive frequency response of the telephony device shall be measured according to IEEE Std 269-2004 and IEEE Std 1329-1999, respectively. If required, the measurement shall be performed in an anechoic chamber. Not all EUTs require testing in an anechoic chamber, but rather may be characterized in other environments. The receive frequency response is the conversion ratio of the electrical input to the acoustical output as a function of frequency. The electrical input signal is applied at the battery feed circuit or at the reference CODEC, as appropriate, for the analog telephone or the digital telephone. The sound output pressure of the handset is measured in the appropriate Ear Simulator for the EUT.b

Using the same EUT, the measurements of paragraph two of this subclause shall be repeated, but with the EUT in its RF test position in the RF test chamber with the RF off. The same electrical input signal as in paragraph two is applied at the battery feed circuit or at the reference CODEC, as appropriate, for the analog telephone or the digital telephone, respectively. The tubing arrangement described above shall be used to deliver the sound pressure to the measuring microphone. The measuring microphone measures the sound output pressure.

For each operating mode, the receive frequency response measured in paragraph three of this subclause shall be subtracted from the receive frequency response measured in paragraph two of this subclause to obtain the correction factor as a function of frequency.

It shall be verified that the acoustical noise in the RF chamber does not affect the acoustical measurements. A procedure analogous to that of Error: Reference source not found may be used to accomplish this check.

For the speaker mode, the EUT should be positioned as far as possible from other objects in the chamber. It shall be verified that moving objects within the chamber do not affect the acoustical measurements.

When the EUT is monitored during an RF immunity test, the correction factor for the operating mode as a function of frequency that was obtained in the calibration described above shall be added to the measured sound pressure.

13.2.2 Far-end monitor

Monitoring of the far-end is accomplished by an electrical measurement of the audio signal outside of the RF test chamber. The telephony device shall be placed in the operating mode to be tested, i.e., powered in the off-hook condition with the transmit transducer active.

For an analog telephone, an analog feed circuit per IEEE Std 269-2004, without a line loss simulator, is used. The measurement is made across a 600 Ω termination.

For a digital telephone, a digital connection shall be made to a reference CODEC. If the digital output can be accessed, the digital code may be referenced; it is preferred that the measurement be made using the digital output of the CODEC. Alternately, the measurement may be made at the analog output of the reference CODEC.

b See IEEE Std 269-2004 for guidance on selection of the appropriate ear simulator.

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14. Near-field test procedure

This clause describes the test facility, equipment, and procedures to be used when performing measurements with a dipole in close proximity to the EUT.

Testing by use of dipole illumination in the near-field has two significant advantages. First, it requires much lower power to achieve the target field strength. This represents a significant savings in test equipment cost. Second, near-field dipole illumination of this kind is very similar to the kind of environment created by real devices. In the near-field, the E-Field and H-Field do not have a constant relationship but rather are determined by the characteristics of the source. Near-field exposure recreates this condition. A third advantage is that the lower power testing poses less of a risk of interference to the terrestrial networks operated by local service providers.

In the test described in this clause, a dipole is energized and moved over the surface of a plane at a defined distance from the EUT. For example, the dipole is moved vertically a fixed distance from the center of rotation of the EUT and horizontally over the top of the EUT. In addition, the dipole is rotated so as to present two orthogonal orientations for each plane scanned.a

Near-field scanning does not require that the test be performed in an RF shielded chamber. The lower power used in near-field scanning may allow the test to be performed in an open environment. When near-field or exploratory testing is performed outside of a RF shielded environment, there is a risk of interference with the terrestrial networks operated by local service providers. Before performing such a test, it shall be determined if it is required to obtain permission from the local licensee or from a regulatory authority, e.g., FCC.

14.1 Test setup and validation

This subclause describes the test facility, equipment, and procedures to be used when performing measurements with a dipole in close proximity to the EUT.

14.1.1 Check for RF interference to test equipment

The procedure in this subclause is performed to assure that the instrumentation that will be monitoring the EUT is not itself susceptible to the RF. Hence, this procedure is performed to assure that when a response is recorded during the test, it is, in fact, coming from the EUT.

a) Setup the test equipment as intended for the test.

b) With the RF off, record the readings on any monitoring instrumentation.

c) Illuminate the dipole and perform the scans over planes, the frequency ranges and power levels intended for the test.

a It should be noted that the tip of a dipole is dominated by the E-Field and its center by the H-Field. As the dipole is moved up and down a product, the center will be exposing the product to high H-Fields while the tips will be presenting high E-Fields. Depending on the nature of the sensitive circuit within the EUT, it may respond more strongly to one or the other of these field components.

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Systems in High Reliability Installationsd) Record the highest reading from the monitoring instruments.

The monitor instrumentation shall not exceed 10 dB below the limit to be measured and 20 dB below the limit should be provided. If the instrumentation does not meet this requirement, additional isolation shall be provided.

14.1.2 Device support and check for reflections

The EUT shall be supported in such a way that there are no significant RF reflecting objects within a distance of at least two wavelengths at the frequency of measurement,b or at a distance such that the total reflections from these objects is kept at least 20 dB below the desired direct test signal. If RF absorber is used, the separation distance may be reduced, so long as the effect of reflections is at least 20 dB below the desired test signal strength. The purpose of a two-wavelength distance to the nearest significant RF reflective object is to maintain at least a 20 dB reflection loss due to these objects. If it is not practical to measure the reflection loss, then the two-wavelength spacing rule may be used. Support structures such as expanded foam and very low dielectric constant plastics may be used for supporting the EUT.

A check for reflections may be made. To check for reflections, standing waves, or other influence from nearby objects, an isotropic probe is attached to the illuminating dipole at the distance the EUT will be placed. The illuminating dipole and the probe are moved so that the probe and dipole maintain a fixed relationship. Perform the intended scans and compare the results.

The RF ambient shall be >20 dB below the intended test field strength. If the RF ambient is within 20 dB of the intended test field strength, further isolation of the test environment shall be provided.

14.2 Test scans and positions

In the test described in this clause, a dipole is energized and moved over the surface of a plane at a defined distance from the EUT. The dipole is moved vertically, using one of two scanning methods and horizontally over the top of the EUT. The dipole is rotated by 90° around an axis normal to the surface being scanned to present two polarizations of RF exposure.

It should be noted that the tip of a dipole is dominated by the E-Field and its center by the H-Field. As the dipole is moved over a product, the center will be exposing the product to high H-Fields, while the tips will be presenting high E-Fields. Depending on the nature of the sensitive circuit within the EUT, it may respond more strongly to one or the other of these field components.

Two methods of scanning the vertical surface of the product are provided. In the first method, a set of planes is defined, following the major contours of the product, and a scan is performed 25.0 mm ±1.0 mm from each plane (see Figure A-5). In the second method, a circle is drawn around a product with the EUT defining the diameter of the circle, and a scan is performed 25.0 mm ±1.0 mm from the circle (see Figure A-6).

When using scanning method one, a set of planes shall be defined using the major contours of the product. The dipole is then moved across a surface 25.0 mm from the surface of the product.

b For 698 MHz the wavelength is 43 cm, so the separation distance is 86 cm. If testing is done only in the cell phone bands, the lowest frequency is 824 MHz, 36.5 cm; the separation distance is 73 cm.

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Figure A-5—Scan method 1Vertical scans are conducted over a set of planes

In the second method, the EUT is rotated, and the dipole is vertically at several positions around the product. For the vertical scan, in which the product is rotated, a circumference shall be defined that encompasses the product. The dipole shall be located 25.0 mm beyond this circumference. Note that when the portion of the product that touches the circumference is facing the dipole the dipole, will be 25.0 mm from the EUT surface. As the EUT is rotated, its distance from the dipole may be farther away. The dipole shall scan positions separated by 60° around the circumference of the circle around the product.

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Figure A-6—Scan method 2Vertical scans are conducted around the circumference of the EUT

For both scan methods the scan over the top of the EUT is performed by moving the dipole in a horizontal plane 25.0 mm above the highest point on the EUT. For the scan in which the dipole is moved horizontally over the surface of the product, the dipole shall be oriented in each of two orthogonal orientations as it scans the EUT.

For both methods the width of the scan, both vertical and horizontal, shall expose the edges of the product to both the dipole tip and center.

For both methods a coarse, preliminary scan may be performed in which the dipole is moved in larger physical steps and using larger frequency steps. After the preliminary, pre-screening scan, the dipole shall be returned to the position(s) and orientation(s) of maximum response, and a more detailed scan performed.

14.3 Transmit power

For the near-field test procedure, the power into the dipole may be used for determining the field strength. The relationship between RF power into the dipole to field strength is assumed to be that of a dipole radiator with a 3 dB margin added to account for dipole VSWR and other variables.

Equation (1) shall be used to determine the power into the dipole, in Watts, from the required field strength, in V/m:

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Systems in High Reliability InstallationsField Strength (V/m) = (30 × Power (W)/r2)1/2 × 1.74 (1)

where

Power (W) – Net power into the dipole

r – Intended distance between the dipole and EUT in m

The factor of 1.74 is the linear value for 2.4 dB of dipole antenna gain added to 3 dB margin, 2.0 in linear units, to compensate for VSWR and other variables.

Therefore, the Power into the dipole is calculated from Equation (2):

Power (W) = (Field Strength (V/m) / 1.74) 2 × r2 / 30 × 2.0 (2)

The calculated power must be adjusted when dipoles are used above or below their resonance frequency to adjust for the difference in antenna efficiency.

A directional coupler may be used to measure the forward and reverse power, in order to determine the required net power.

14.4 Test modulation

The test modulation shall be as defined in the test profile. Preferably waveform files, recording actual transmitters that have been identified as worst-case interferers will be used in defining the test profile.

14.5 RF immunity test procedure

a) Place the EUT in the intended test position and connect all necessary monitors and support equipment.

b) Place the dipole in position for the vertical scan of the EUT.

c) Perform the coarse scan and identify area(s) of maximum response.

d) Scan the area(s) of maximum response using the required physical and frequency step sizes. Scan through the required frequency range.

e) Raise or lower the dipole so that at least one tip and the center of the dipole traverse the height of the product. Scan the frequency range at each step during the vertical scan.

f) Rotate the EUT through each of the required 120° rotations, repeating the dipole vertical scan at each position.

g) Change the dipoles polarization and repeat steps c) and f).

h) Move the dipole for the horizontal scan over the top of the product.

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15. Measurement uncertainty

Most treatments of measurement uncertainty address only the uncertainty of the instrumentation chain. However, in addition to these factors there is uncertainty introduced from two other areas. The first is the test setup variability of the EUT. Particularly for complex equipment, especially where significant wires are involved, the EUT can be setup for test in a very wide variety of ways. Variations in the EUT setup can result in variations in the test results.

The second area of uncertainty is manufacturing variation. The EUT is a representative sample of a population of devices. The variability of the population must be comprehended if the immunity experienced in the installed environment is to meet required levels.

For this standard an assessment of all three contributors to evaluation shall be provided, that coming from the instrumentation chain, EUT setup and manufacturing variance. In order to assure the delivery of the required levels of immunity the total measurement uncertainty shall be added to the immunity measured and the sum used when determining compliance with the limit.

All uncertainty calculations, estimates shall be in accordance with NIST policy stated in Appendix E to NIST Technical Communications Program, Subchapter 4.09 of the Administrative Manual, as reproduced in Appendix C of NIST Technical Note (TN) 1297, 1994 Edition. The NIST policy is based on ISO Guide to the Expression of Uncertainty in Measurement (JCGM 100:2008, here after called the GUM). The U.S. version of the GUM is ANSI/NCSL Z540-2, American National Standard for Expressing Uncertainty — U.S. Guide to the Expression of Uncertainty in Measurement, 1997 [3]. Either the GUM or Z540-2 shall take precedence in the event of disputes. However, the Guide is explained in TN 1297. JCGM 101, 102 and 104 provide additional guidance regarding estimation of measurement uncertainty.

16. Glossarya

a Definitions are from The Authoritative Dictionary of IEEE Standards Terms [O2] unless otherwise noted.

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Annex A

(informative)

EMC standards and guidelines

The following standards and documents contain material on radiated RF immunity testing or mitigation and potentially will be useful in addressing RF immunity issues or developing mitigation measures.

1. IEC 60601-1-2:2007, Medical electrical equipment—Part 1: General requirements for basic safety and essential performance—2. Collateral Standard: Electromagnetic compatibility—Requirements and tests.a

2. IEC 61000-4-3:2006, Electromagnetic compatibility (EMC)—Part 4: Testing and measurement techniques—Section 3: Radiated, radio-frequency, electromagnetic field immunity test.

3. MDS-201-0004: 1979, Electromagnetic Compatibility Standard for Devices (FDA voluntary guideline).b

4. MIL-STD-461F, Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment, 2007.c

5. Reviewer Guidance for Premarket Notification Submissions: November 1993 (an FDA reviewer guidance document).d

aIEC publications are available from IEC Sales Department, Case Postale 131, 3, rue de Varembé, CH-1211, Genève 20, Switzerland/ Suisse. IEC publications are also available in the United States from the Sales Department, American National Standards Institute, 11 West 42nd Street, 13th Floor, New York, NY 10036, USA, http://www.iec.ch.bAvailable beginning on p. 19 of the file at http://www.fda.gov/cdrh/ode/638.pdf.cMIL-STDs are available from Defense Printing Service Detachment Office, 700 Robbins Avenue, Philadelphia, PA 19111-5094, USA. (http://www.assistdocs.com)dAvailable as Excerpts Related to EMI from Nov. 1993 Anesthesiology and Respiratory Devices Branch at http://www.fda.gov/cdrh/ode/638.pdf.

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Annex B

(informative)

Characteristics and types of RF transmitters

B.1 Characteristics of RF transmitters

B.1.1 RF propagation and the relationship between frequency and wavelength

The frequency of radio waves (tens of kilohertz and up) permits them to propagate through space. The frequency and wavelength are related by the speed of light, which (in a vacuum) is a constant, by the following equation:

frequency wavelength = speed of light = 3 108 m/s (B.1)

The equation is easiest to use when the wavelength is in meters and the frequency is in megahertz:

frequency (in MHz) wavelength (in m) = 300 (B.2)

Table 4 provides example solutions to this equation.

Table 4 – Example solutions to equation B.2

Frequency (MHz) Wavelength (m) Frequency (MHz) Wavelength (m)1 300 100 33 100 300 110 30 1000 0.330 10 3000 0.1

Because RF electromagnetic energy propagates through space, it can affect devices that are located remotely to the source of RF energy. Interference can be more likely to occur at RF frequencies at which the cables, wires, printed circuit board traces, and components of a device are odd multiples of 1/4 of the wavelength. However, in intense RF fields and/or for susceptible circuitry, effects can be observed for longer and/or shorter conductors, including those as small as approximately 1/20 of the wavelength.

B.1.1.1 Electric and magnetic fields

RF energy is comprised of two interrelated components, electric (E) and magnetic (H) fields. It is usually expressed in terms of the magnitude of the electric field vector, in volts per meter, but can also be measured in terms of the magnitude of the magnetic field vector, in amperes per meter. For measurements in the near field, where the distance from the source is small compared to the wavelength, the term electric field strength or magnetic field strength is used according to whether the resultant E field or H field is measured. At lower frequencies (below 100 MHz), measurements are typically made in the near field. The E and H field strengths fall off with respect to the distance from the source. However, very close to a source, such as a mobile (cellular or PCS) telephone, the field strengths can be quite high.

Unintended coupling of E fields to devices usually occurs through relatively straight cables, wires, and printed circuit board traces in the device, and can occur at large distances from the RF source. Unintended coupling of H fields to devices usually occur through coiled cables, wire loops, and loops formed by printed circuit board traces in the device, and usually occur very close to the RF source.

B.1.2 Sources of RF energy

RF energy can be emitted by natural phenomena, as well as by man-made sources. Natural sources include lightning and electrostatic discharge (ESD). Man-made sources can emit RF energy intentionally or unintentionally.

Intentional emitters use RF energy for communications, control, or for sensors. Intentional emitters used for communications include hand-held transceivers, mobile (cellular and PCS) telephones, telemetry transmitters and repeaters, radio paging systems, mobile radio transmitters, citizens band (CB) and amateur radio transmitters, television (TV) broadcast transmitters, AM and FM radio broadcast transmitters, radars, wireless radio local area networks (LANs), wireless personal digital assistants (PDAs), and RFID readers. Intentional emitters used for control include garage door openers, keyless entry, and radio remote-control transmitters.

Unintentional emitters include any electrically powered equipment, even equipment that is battery powered. Unintentional emitters of RF energy include computers, electronic games, and radio and TV receivers. The emissions of some equipment are regulated by the FCC. However, these regulations do not require that RF emissions from unintentional emitters be zero, but rather permit such equipment to emit a very low level of RF energy.

Devices having insufficient electromagnetic immunity could be affected by any one of these sources. However, this recommended practice is limited to portable, intentional emitters with output power of 8 W or less.

B.1.3 Dynamic Power Control

Many wireless networks and communications services use dynamic power control. Dynamic power control is used to insure that an optimal balance is maintained between having enough RF power to effectively communicate but not more, so as to save battery life and allow other users of the band to operate without interference. The cellular phone network aggressively uses dynamic power control to optimize network performance.

For mobile phones operating on conventional networks, output power is regulated by individual base stations based upon receive signal strength from the mobile phone. Power is adjusted many times per second, and maintained at a sufficient level to obtain robust connection without overly taxing the network resources, battery, or causing unwanted side-channel interference. The dynamic range of output power associated with conventional 850 MHz GSM networks is from a maximum of 2 W (peak) / 250 mW (average) to a minimum of 0.02 W (peak) / 2.5 mW (average). The dynamic range of output power associated with conventional 1900 MHz GSM networks is from a maximum of 1 W (peak) / 125 mW (average) to a minimum of 0.001 W (peak) / 1.25 mW (average). Other air interfaces have similar dynamic ranges.

While the base station normally controls the RF output power of mobile phones to be the lowest that can provide adequate communications, there are times when the power goes to maximum, such as when the phone is ringing.

B.1.4 Effective radiated power

The effective radiated power of an RF transmitter is a function of its output power and antenna efficiency at the transmission frequency. These parameters are fixed for most transmitters. However, for devices that use dynamic power control, like mobile (cellular and PCS) telephones, the output power is controlled over a wide range, up to its maximum rating, by the base station. In general, the further away and/or the more shielded the use location is from the nearest base station, the higher the output power of the mobile telephone will be, up to its maximum rated power.

A transmitter having a higher power can affect a device at a greater distance than one having a lower power at the same frequency. EMI problems in facilities can be minimized by using communications equipment having the lowest possible output power that can accomplish the intended purpose. Another way of achieving low power transmissions inside a facility is through telecommunications system engineering. The organization can select, e.g., particular mobile (cellular or PCS) telephones to be used in the facility and manage the output power of the hand-held transmitters to keep it low while they are in the facility. This can include the installation of local or in-house base stations.

B.1.5 Field strength versus distance

The field strength of an RF transmitter is relatively high directly adjacent to the antenna. In the near field (up to several wavelengths from the antenna), the field strength falls off very rapidly. In free space, at distances greater than several wavelengths, the field strength falls off as the inverse of the distance (1/d), i.e., for every doubling of the distance, the field strength is reduced by one-half. However, in most facilities, reflections from structures and objects result in a very complex relationship between distance and field strength. As a consequence, field strengths can occasionally be higher than expected at greater distances, and lower than expected at lesser distances (see [O19]). This can be particularly true inside a shielded room (see [O15]).

Even so, radiated EMI problems in facilities can generally be minimized by managing (increasing) the distance between RF transmitters and susceptible devices (including cables, sensors, and electrical accessories).

B.1.6 Modulation

An RF signal without modulation is known as a continuous wave (CW) signal. In order to carry information, the RF signal is usually modulated in one or more of the following ways: amplitude modulation (AM), frequency modulation (FM), phase modulation (PM), and/or pulse modulation. In AM, the information is carried in the variations of the field strength, which can be as much as 100%. In FM, the information is carried in small changes in the frequency of the signal. In pulse modulation, the amplitude, duration, or time position of pulses in a pulsed RF signal is varied. Morse code is a simple form of pulse modulation. Some (e.g., digital) mobile (cellular and PCS) telephones use both FM and time division multiplexing (TDMA), a form of pulse modulation.

It is often the modulation that interferes with susceptible electronic equipment, particularly AM and pulse modulation. The modulation riding on the CW RF carrier can be demodulated by nonlinear circuit elements such as semiconductor junctions in diodes, transistors, and integrated circuits. Demodulated waves can appear as unintended AC signals or can be filtered by circuit capacitance, resulting in unintended DC off-sets.

Two-way radio communications usually consist of a series of short transmissions. This on-off keying can be likened to very-low-rate pulse modulation and can affect susceptible circuitry, even in the case of FM transceivers.

B.1.7 Duty cycle

The duty cycle (percent on-time) of RF transmissions differs widely among transmitters. AM, FM, and TV broadcast transmitters operate continuously. Hand-held transceivers, CB, and amateur radios transmit only while the talk button is pressed (keying). When active, mobile (cellular and PCS) telephones transmit either continuously or intermittently, depending on the technology. Mobile (cellular and PCS) telephones also transmit intermittently in the standby mode, to register their location with the base station (registration).

Some devices are particularly susceptible to keying and/or to intermittent transmissions.

B.1.8 Spurious and out-of-band emissions

Most RF transmitters emit some small amount of energy outside the designated carrier frequency or band of transmission. Spurious emissions are emissions on a frequency or frequencies that are outside the bandwidth necessary for transmission of information. Spurious emissions include harmonic emissions, parasitic emissions, intermodulation products and frequency conversion products, but excluding out-of-band emissions. Out-of-band emissions are emissions on a frequency or frequencies immediately outside the necessary bandwidth that results from the modulation process, but excluding spurious emissions

Spurious and out-of-band emissions are regulated in the US by the FCC and are required to be very low, e.g., 50 W for a 1 W mobile telephone. Therefore, they would not be expected to affect devices, even those that include RF receivers. For RF transmitters operating within frequency bands licensed from the FCC (or from analogous agencies in Europe and throughout the world), out-of-band emission levels are generally low due to bandpass filters incorporated to comply with tight regulation, and thus would not be expected to be a significant threat to devices. As an example, current FCC Part 15 compliance specifications require the power of any spurious emission on a mobile phone to be attenuated by at least 43 + 10log(P) dB or 60 dB, whichever is the lesser attenuation (for a 1 W transmitter = - 13 dBm or 50 W). In Europe, the ITU RR Ap 3 specification is -16 dBm or 25 W for a 1 W transmitter in the 900 MHz band (< 960 MHz) and 100 W for a 1 W transmitter with a carrier frequency of 960 MHz – 17.7 GHz. In practice, the level of out-of-band emissions on mobile phones is even lower so they can operate on their designated channel frequencies without disrupting neighboring channels.

B.1.9 Faults

Because they are electronic devices, RF transmitters can experience component failures. In most cases, this would result in a decrease in the RF output power or the transmitter becoming ineffective. A decrease in output power would make it less likely to affect a device. Becoming ineffective would cause use of the transmitter to be discontinued until it could be repaired or replaced.

In the case of mobile phones as well as some (networked) radios and other transmitters, faults increasing the output power are unlikely due to feedback control and power-management loops. In addition, the power amplifier (PA) is often capable of delivering the nominal output power only in specific loading conditions and the input impedance of the antenna is optimized to present the proper load to the PA. If failure involving the antenna or any other element in the matching chain occurs, the result would most likely be a decrease in the actual radiated power, not an increase. Further, the power amplifier components themselves are generally rated at or slightly below the maximum rated power of the handset, so even if an unlikely fault did occur, the power output would never greatly exceed full power as defined by the normal specification or the PA would fail. With regard to the battery, most mobile phones have maximum current protection that prevents shorts (especially with lithium batteries, as they have a tendency to get hot and physically disrupt). Even if maximum current was delivered to the handset through a short, the battery has a finite life, so a handset failure of a type causing a surge would not last long - it would have to occur in the immediate space and time frame during use of a susceptible device.

Faults in filters would also not be a typical source of increased output power of out-of-band emissions. Because filters are in-line components, faulty filters would tend to diminish out-of-band emission levels as the whole circuit would either be disrupted or become mismatched and power would not get out of the antenna efficiently. The most significant reason that RF transmitter faults are unlikely to cause EMI, however, is that the RF equipment is likely to be inoperable under fault conditions. The majority of such hypothetical scenarios, themselves already highly unlikely, would result in equipment that could not communicate properly to its respective network, and in such a case would tend not to be used for any significant period of time.

B.1.1 Architectural effects

The architecture of a facility can significantly affect the field strengths that result at any given location (see [O25]), from RF transmitters both inside and outside the facility. Structures such as solid or screen metal walls or siding can attenuate RF signals entering the facility or the treatment area. Steel reinforcing rods in concrete walls and floors can provide a certain degree of shielding, as can the earth itself (e.g., in the basement). However, RF can pass through walls, floors, and ceilings. Standing waves can occur within a building, resulting in floor-to-floor propagation patterns that differ from what might be expected (see [O19]). This can have particular implications for rooftop transmitters and their effect on equipment within the building. Also, a wide range of RF frequencies can pass readily through glass windows, depending on the reflection/glare reduction material used (if any) and the adequacy of the bonding (if any) between the reflection/glare reduction material, the window frame, and earth ground.

Some very sensitive devices (e.g., electroencephalographs (EEGs) and audiometers) are routinely used in shielded rooms or booths. Magnetic resonance imaging (MRI) is operated in a shielded room to prevent EMI from affecting the imaging system. While x-ray shielding can be effective for x-rays, windows and door seams in x-ray shielded rooms generally do not attenuate higher-frequency RF fields, and seams in the x-ray shield can re-radiate RF.

Depending on their placement, however, metallic objects (e.g., steel reinforcing rods, metal cabinets, neigh-boring buildings) can also reflect RF fields. If the direct and reflected RF waves arrive in phase, the field strength will be higher than that of the original incident wave. Also, large metallic objects such as heating/ cooling ductwork and/or electrical wiring and conduit can re-radiate RF within a facility.

B.1 Types of RF transmitters

B.2.1 Portable RF transmitters

The most prevalent portable RF transmitters are mobile (cellular and PCS) telephones. They periodically radiate RF energy while they are turned on, even if a telephone call is not in process. A mobile telephone ceases to be an RF signal source only when the power is switched off. Other portable transmitters include wireless personal digital assistants (PDAs); wireless local-area network (wLAN) interfaces; hand-held transceivers used by emergency, maintenance, and security personnel, as well as amateur radios used for emergency communications or for recreation.

B.2.2 Mobile RF transmitters

Mobile radio transmitters can be installed in vehicles and aircraft. These include CB and amateur radios, as well as radio transmitters in ambulances, police and fire vehicles, delivery vehicles, taxis, shuttle buses, and aircraft, including helicopters.

Mobile transmitters intended to be installed in vehicles and aircraft are excluded from this recommended practice because their higher power levels would necessitate large test areas and large initial test distances.

However, mobile RF transmitters can cause EMI at greater distances than can portable RF transmitters because of their higher power levels.

B.2.3 Fixed RF transmitters

Fixed RF transmitters include AM, FM, and TV broadcast stations as well as a multitude of RF transmitters used for paging, short-wave radio, aeronautics, cellular base stations, radio LANs, amateur radio, and many other purposes. In a healthcare facility, the in-house radio paging system is a likely source of high-field- strength RF.

Fixed transmitters are excluded from this test procedure because it is difficult to vary the spatial relationship between the device under test and a fixed transmitter in a meaningful way, and they usually cannot be switched off and on to determine correlation with malfunctions.

B.2.4 Transmitter frequency bands, output power levels, and estimated field strengths at 1 m (39 in)

For prevalent RF transmitters, Table B.2 presents the frequency bands, output power levels, and estimated field strength at a distance of 1 m (39 in). The field-strength estimates are presented in volts per meter. Most were calculated using Equation (F.1), which appears in Annex F`.

Table B.1 Typical transmitters, output power levels,and estimated field strengths at 1 m (39 in)

Product Frequency (MHz) Power (W) Field strengthat 1 m (V/m)

RFID readers < 0.135 (inductive coupling)

(72 dBµA/m)

RFID readers 6-8, 13, 27, 433, 865, 900, 2450, 5800

> 2-5 (433MHz limited to 55,000uV/m@3m)

Paging transmitters 49 250 110a

Mobile radios 138–470 25 35a

Hand-held transceivers 27, 49, 138–470 5 15a

Police/ambulance 138–900 10–100 22–70a

Commercial BW and Public Safety (mobile)

698-806 1-2

Wireless LANs 912, 2400, 5GHz 0.1 -0.25 2.2 – 3.1Wireless personal digital assistants 896–940 2 10Radio modems 896–901 10 22Cellular telephonesb 800–900 0.6 5.4Personal communications satellite telephones

1610–1626.5 1 7

Licensed PCS equipment 1850–1910 1 7BWA (3G / IMT, WiMAX mobile) 2.5 -2.689 1-2BWA (Fixed)) 3650-3700 1-25Public Safety 4940-4990 2CISPR 11, CISPR 22 c 25–1000 0.04 10-6 0.0014 d

a. For these transmitters, 1 m (39 in) is in the near-field. Therefore, these field strength estimates can be very inaccurate

b. Some Global systems mobile (GSM) cellular telephones, particularly in Europe, use higher power levels.c. Industrial, scientific, and medical (CISPR 11) devices that are not intentional emitters of RF and information

technology equipment (CISPR 22), each of which are in compliance with the respective emissions standard.

d. This represents the approximate maximum RF field strength at a distance of 1 m (39 in) from this equipment.

ANSI PC63.24/D1.7Recommended Practice for In-Situ RF Immunity Evaluation of Products, Instrumentation, and Control


Annex C

(informative)

Alternative RF Test Sources and Test Methods

A.1 Representative waveforms

Representative waveforms such as those specified in Appendix 6F of RTCA DO-294 (2007) can be used. This section describes these waveforms and the wireless technologies for which they can provide representative testing.

Evaluation of common wireless communication signals (mobile phones, data communications, and professional radio) was performed by the RTCA SC202 in the development of DO-294 (2007). DO-294 offers guidelines for the use of passengers’ RF transmitters in commercial aircraft. SC202 concluded that the most probable pathway to significant EMI events in aircraft was direct coupling of RF to wires and circuitry of navigation and communication equipment, not via direct in-channel emissions that might overlap with sensitive avionic receivers mounted outside the aircraft. The same would be expected to apply to devices, such that coupling with wires and circuitry would be the main EMI pathway.

Table C.1 Representative signal types (copied with permission from RTCA DO-294)

Application

Access schemes

Mobile phone Data communication Professional or personal mobile radio

TDMA (time division multiple access)

CSMA (carrier sense multiple access)

GSM, i-DEN, IS-136 DAMPS, PDC, PHS

IEEE 802.11a, b, g, ZigBee (IEEE 802.15.4)

TETRA

CDMA (code division multiple access)

FDMA (frequency division multiple access)

UMTS, NAMPS, AMPS, CDMAone, CDMA2000

MOBOTEX II, Bluetooth

TETRAPOL, EDACS, Project25/APCO25, PMR446, MPT-1327



NOTE—Support for AMPS terminated in North America in February 2009. If AMPS is no longer used in your area, you do not need to test using AMPS signals.

In DO-294 Appendix 6F, wireless communication signals are grouped in two categories with respect to their relative risk for generating EMI, and two simplified basic signal waveforms are specified to replicate these categories. For further information regarding the assumptions made in the design of the two test signals, see DO-294 Appendix 6F.

For TDMA pulse modulated communication signals (e.g., GMS, iDEN, PDC, PHS, TETRA, UMTS TDD mobile phones) and CSMA pulse modulated data communication signals (IEEE 802.11a, IEEE 802.11b, 802.15.1 / Bluetooth, IEEE 802.15.4 / Zigbee), a representative pulse modulated signal having a pulse repetition rate of ~ 200 Hz (~ 5 ms period) and a pulse duration of ~ 625 s is suggested.

For signals that are phase- or frequency-modulated (e.g., FDMA, CDMA, QPSK / OQPSK, BPSK, GMSK), a CW test signal of constant signal amplitude is suggested. Examples of communication technologies employing these schemes include CDMA, UMTS FDD, CDMA2000, NAMPS / AMPS, MOBITEX, PMR446, APCO25, MPT-1327, TETRAPOL, EDACS, and many common two-way radio schemes.

The generation of test waveforms requires signal generators and might require amplifiers, but it allows testing at an initial 20 V/m incident field strength to be achieved from a far-field distance. In addition, this equipment can generate higher powers that could be more likely to reveal device susceptibility. It also allows larger regions of the test area to be illuminated for a more comprehensive assessment.

The two representative waveforms described above, transmitted on an appropriate channel within the existing cellular (824-848 MHz) and PCS (1850-1910 MHz) bands, should provide sufficient testing for existing mobile phones. In addition, such test waveforms should also be appropriate for emerging communication bands including 700 MHz WCS, 1.7 GHz, 2.3 GHz AWS, and 2.5 GHz BWA that have been allocated by the FCC and might be incorporated into mobile phones. If other technologies are anticipated to be used in the facility, additional testing should be performed. For example, additional pulse-modulated testing at 800 MHz should be included to address iDEN technology and CW testing at 2 GHz should be included to address 3G UMTS FDD signals. In addition, pulse-modulated and CW testing should be performed at 2450 MHz to address WiFi (IEEE 802.11x), Bluetooth, and other data communication signals. If European frequencies are to be used, additional testing should also be performed (i.e., pulsed signals to address GSM at 890-915 MHz and 1710-1785 MHz, and CW signals to address UMTS at 2-2.2 GHz).

Possible test combinations:

Cellular band (824-848 MHz) testing: o TDMA signalo CW signal

PCS band (1850-1910 MHz) testing:o TDMA signalo CW signal

Additional test combinations:



iDEN (806-824 MHz) testing:o TDMA signal

3G / UMTS FDD / CDMA2000 (1920-1980) testing:o CW signal

wLAN and wPAN data communication (2400 – 2500 MHz) testing:o TDMA signalo CW signal

wLAN data communication (5150 - 5825 MHz) testing:o TDMA signal

New and emerging technologies (700 MHz WCS, 1.7GHz, 2.3 AWS GHz, and 2.5GHz BWA):o TDMA signalo CW signal

A.2 Recorded signal files

As another alternative to using off-the-shelf transmitters, and for the purpose of in-situ testing of large areas where multiple devices are located, the use of recorded signal files can be considered. This is, however, not the preferred method for most facilities. See precautions in section Error: Reference source not found for in-situ testing. In-situ testing can be performed using near-field exposure with recorded RF signals of actual voice and data communications (e.g., 850 MHz GSM, 1900 MHz GSM, 850 MHz CDMA, 1900 MHz CDMA, 800 MHz iDEN, 2450 MHz 802.11a/b/g, 2450 MHz Bluetooth) at defined incident field strengths. The use of signal recording and generating equipment offers the ability to authentically replicate signal transmission in immediate proximity to a device under test using defined conditions. This method also allows the user to illuminate larger regions of a room or environment (e.g. in situ) to test multiple devices. It also allows testing at higher levels than would normally be encountered using the actual RF transmitters themselves, which would increase the probability of causing interference so that the threshold of EMI sensitivity could be determined. In this procedure, signals used for testing would be previously recorded as in-phase and quadrature (IQ) files from actual RF transmitters (e.g., mobile phones operating on defined air interfaces). Waveform IQ files available for testing would be transmitted by an arbitrary signal generator (ASG) using an appropriate amplifier and dipole antenna.

In a situation where a large number of devices need to be tested within a defined area, far-field testing using the procedures specified in IEC 61000-4-3 might be considered, using the recorded IQ files instead of the 80 % AM signal. This would provide an advantage of simultaneously testing many devices, but would require a much higher power level, which could be problematic and in addition might not replicate the complex field patters emitted from portable RF transmitters in the near field.

Any in situ testing should follow the recommendations of Error: Reference source not found.

Possible test combinations:

806-824 MHz iDEN 824-848 MHz AMPS 824-848 MHz CDMA 824-848 MHz GSM 1850-1910 MHz CDMA 1850-1910 MHz GSM 1920-1980 UMTS FDD 1920-1980 CDMA2000






Annex D

(informative)

Estimation of incident field strength and minimal test distance without the

use of an E-field meter

The tables below can be used to approximate maximum power setting for a given mobile phone signal technology as well as the E-field strengths in free space at incremental distances for a given known output power. Error: Reference source not found shows data, experimentally obtained with an E-field meter, that corroborate the field strength calculations in Table D.2. At ~ 0.5 m, field strengths measured in an anechoic environment from a variety of mobile phone transmitters were ~ 20 (± 10) V/m. Also from Error: Reference source not found, at 1 m these levels fall to ~ 3 V/m with a similar margin of error. For signals that are continuous with respect to time and not pulse-modulated (e.g., AMPS, CDMA), this is an approximation of the incident field strength and can be used to determine the 20 V/m distance at which to begin testing (i.e., ~ 0.25 m to 0.5 m). For signals that are pulse modulated (e.g., iDEN, GSM), the value captured by the E-field meter and displayed in Error: Reference source not found is probably somewhere between a peak and an average level (depending upon the response time of the probe and its ability to accurately capture true peak field strength). A conservative approach would be to assume that the field strength measurements in Error: Reference source not found result from the average power values, and multiply the average field strength by the pulses per frame (iDEN = 6, GSM = 8) to get an approximate peak field strength value. This peak value (relevant for EMI testing) can then be used to approximate the starting distance for testing (i.e., ~ 20 V/m).


The near-field / far-field transition for EM waves is dependent upon many factors, including the dimensions of the antenna and the wavelength of the signal. For approximation of field strengths from mobile phones incident upon devices, it will be considered here as ~ ½ wavelength. At 900 MHz, this would be ~ 20 cm, and at 1900 MHz it would be ~ 10 cm. Another approximation commonly made is that in the far field, the field strength varies inversely with the distance. Therefore, if a source (e.g., mobile phone transmitter) delivers an approximate incident field strength to a device of ~ 20 V/m at a distance of 50 cm, it should deliver an approximate field strength of ~ 10 V/m at a distance of 1 m.

Table D.1 Maximum transmit power of common mobile phone technologies

Signal type Peak power Average power

Pulses per frame

800 MHz iDEN ~ 2 W ~ 600 mW 6850 MHz AMPS ~ 600 mW ~ 600 mW n/a850 MHz CDMA ~ 250 mW ~ 250 mW n/a850 MHz GSM ~ 2 W ~ 250 mW 81900 MHz CDMA ~ 250 mW ~ 250 mW n/a1900 MHz GSM ~ 1 W ~ 125 mW 82000 MHz WCDMA ~ 250 mW ~ 250 mW n/a



Table 5 - Predicted electric field strength values at incremental distances from test transmitters (adapted from ANSI C63.9, Annex I)

Mobile phones operating in constant transmit (test) mode will approximate a normal GSM signal transmitting at a rate of once every 4.6 ms. Under normal conditions when GSM phones are linked to the network and nobody is talking on the phone, it will often employ a delayed transmission (DTx) protocol reducing the number of transmissions and sending white noise to the listener. This further reduces the RF emissions from the transmitter. This is one of several reasons why phones “hooked to the network” in a live call are not recommended as test sources.

Chamber Measurements

0.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

0 0.5 1 1.5 2 2.5 3 3.5

Distance (in meters)

E-F

ield

(in

V/m

)

iDEN (~200 mW)

AMPS (600 mW)

TDMA-800 (250 mW)

TDMA-1900 (250 mW)

GSM-900 (250 mW)

GSM-1800 (250 mW)

GSM-1900 (250 mW)

CDMA-800 (~630 mW)

CDMA-1900 (~630 mW)

ANSI PC63.24/D1.7Recommended Practice for In-Situ RF Immunity Evaluation of Products, Instrumentation, and Control Systems in High Reliability Installations

Figure D-7 - Figure D.1 Experimentally obtained electric field measurements in an anechoic chamber from various mobile phone transmitters (reprinted from [B13])



Annex E

(informative)

Obtaining appropriate experimental licenses

A.3 General

In accordance with the Federal Communications Commission (FCC) regulations, an operator’s license or an experimental license is required to operate specific device in certain frequencies bands. In most cases for testing purposes, an arrangement can be made with the local service provider or licensed operator to perform your testing under their license.

In some cases, this might not be possible, which would then require that the testing be done in a shielded room or that an experimental license for operation in specific bands be obtained.

A.4 How to determine when an experimental license is required

a) For license-exempt radio devices that are operating on US frequencies under Part 15 rules, there is no need to obtain an experimental license to evaluate the product.

b) For license-exempt radio devices that are operating on non-US frequencies, an experimental license is needed to test the devices, as they can cause co-channel interference with other US licensed bands. (Note that though 802.11b/g channels 11 and 12 are not certified for use in the US, they are still in the US frequency band so no license is required to operate in these two bands).

c) For equipment that operates under FCC rules other than Part 15 and specific Part 95 equipment, an experimental license might be required.

The requirements for operation under an experimental license can be found in 47 Code of Federal Regulations Part 5 of the FCC rules.

http://www.access.gpo.gov/nara/cfr/waisidx_01/47cfr5_01.html

A.5 Obtaining permission necessary for RF transmissions

Many common wireless communication networks in the US (e.g., mobile phone cellular, PCS, 700 MHz, 3G) operate on spectrum that is licensed by the FCC to the service provider. The network licensee carefully coordinates all user handsets supported by their network, as well as their base station transmitters, to avoid co-channel interference. As such, any autonomous transmission, by an RF transmitter within this licensed spectrum, that is not managed by the network (e.g., from in-situ test transmitters) must follow appropriate procedures and be coordinated with the local licensee(s) before transmitting, to avoid co-channel interference with the network and violation of FCC requirements. In some cases, simple approval by the local licensee might be sufficient. In other cases, a Special Temporary Authority license must be obtained from the FCC. In either case, communication with, and participation of, the local licensee is not only helpful, but essential in performing the test. In contrast, wireless communication and data services (WiFi,

http://www.access.gpo.gov/nara/cfr/waisidx_01/47cfr5_01.html



Bluetooth, VoIP) that operate on unlicensed spectrum do not require licensee coordination, as long as test transmissions meet applicable FCC specifications, including emissions limits.

A.6 Identification of local licensee(s)

Identification of the local licensees in the test area is possible by searching one of several websites. The Universal Licensing System (ULS) on the FCC website, http://wireless.fcc.gov/uls/index.htm?job=home, allows searches by applying the following procedures:

a) Click on the Licenses button in the Search sectionb) Click Advanced License Search or Market-Basedc) Select two radio service codes: CW - Broadband PCS and/or CL – Cellulard) Click on the Geosearch buttone) Specify state and county or street addressf) Click on the Submit buttong) The appropriate contact information is provided

The local mobile phone network operators (service providers) should be able to assist in identifying the frequency band(s), specific channel frequencies, and air interface(s) that are allocated for mobile phone communication in the immediate test area. They should also be able to help identify appropriate channel frequencies for testing and assist with permission for testing and/or obtaining a test license from the FCC.

A.7 Obtaining a test license (“Special Temporary Authority”) from the FCC

In some cases, a Special Temporary Authorization (STA) will need to be obtained from the FCC before test transmissions take place. In the case of using off-the-shelf mobile phone handsets or other off-the-shelf portable transmitters in a test mode that does not exceed the normal transmit characteristics of networked transmitters, simple approval coordination with the local licensee for test channel frequencies might be sufficient. However, in cases where the local licensee requires an STA, or when using amplification equipment that could exceed the normal transmit characteristics for the frequency band, a test license will be necessary.

An example showing how to obtain an STA online using the https://gullfoss2.fcc.gov/oetcf/els/ page of the FCC website is shown below in A.8.

A.8 Example experimental license application

If an experimental license is needed for more than six months, form 442 on the FCC website should be used, at:

https://gullfoss2.fcc.gov/oetcf/els/forms/442Entry.cfm

The license can be issued for up to two years for developing and testing a system. These licenses take about eight to 12 weeks to obtain.

For shorter duration, apply for a Special Temporary Authority (STA) test license from the FCC’s website. The remainder of this example shows the STA application process. First go to:

http://wireless.fcc.gov/uls/index.htm?job=home



https://gullfoss2.fcc.gov/oetcf/els/

Then click on Special Temporary Authority. (Alternatively, go directly to :

https://gullfoss2.fcc.gov/oetcf/els/forms/STANotificationPage.cfm.)

It gives you the basics as follows:

To provide applicants for experimental Special Temporary Authorization (STA) with the best possible service, we offer the following guidelines:

i. STAs are intended for experiments that will last no longer than six months. Applicants intending to conduct experiments of longer duration should file for a regular experimental license using FCC Form 442.

ii. Applications for STAs are generally processed on a first come, first served basis along with regular applications and should be filed well in advance (at least 30-60 days, if possible) of the desired start day.

iii. In cases where such advance notice cannot be provided, including applications for emergency response systems or those related to national security issues, applicants should make every effort to file as well in advance as possible. If expedited processing is necessary, applicants must provide sufficient justification in accordance with Section 5.61 of the Commission rules.

a. The Commission will evaluate such justification on a case by case basis to determine if expedited processing is warranted.

b. Expedited processing does not bypass the normal application review process. All applications undergo review regarding the potential for an experiment to cause interference to both non-federal and federal systems. Depending on the desired bands of operation, coordination with NTIA may be necessary.

Application Status may be checked online from the The OET ELS Application Search Report or directed to Nancy Hey at 202-418-2432, [email protected]. Application filing questions or ELS filing problems should be directed to [email protected].

Proceed to STA Form

Proceed to STA Form; it takes you to:

https://gullfoss2.fcc.gov/oetcf/els/forms/StaEntry.cfm



mailto:[email protected]

mailto:[email protected]

https://gullfoss2.fcc.gov/prod/oet/cf/els/reports/ApplicationSearch.cfm

https://gullfoss2.fcc.gov/oetcf/els/forms/STANotificationPage.cfm

https://gullfoss2.fcc.gov/oetcf/els/forms/STANotificationPage.cfm

https://gullfoss2.fcc.gov/oetcf/els/



Application For Special Temporary Authority

Use this form for experiments that will last no longer than six months. Experiments of longer duration should use the Form 442 Filing Option.

Enter the following information:

Application Purpose: * New Authorization

uses information from an existing application (i.e. - a template)

Extension New Experiment

File Number:

Is confidentiality required for this filing? * Yes No

Applicant FCC Registration Number (FRN): *

Notice: If you respond "YES" to question 2, please submit a justification as an exhibit along with your application. The justification should state why confidentiality is requested.

* - Indicates that this field must be completed before this page can be submitted.

To submit test filings, you must supply an FCC Registration Number (FRN). Otherwise, in the bottom corner of the STA website, you would need to apply for a FCC Registration Number.

The cost at press time is $50, payable by credit card, and you can check on the status from the main STA website.

Written approval from the local licensee might be required by the case reviewer at the FCC.

https://gullfoss2.fcc.gov/oetcf/els/help/STA_Help.html#frn_number

https://gullfoss2.fcc.gov/oetcf/els/help/STA_Help.html#confidentiality

https://gullfoss2.fcc.gov/oetcf/els/help/STA_Help.html#application_purpose



Annex F

(informative)

Recommendations for mitigation of EMI in facilities

Device users and facility engineers, administrators, architects, and planners can help prevent EMI problems. For additional guidance on this subject, see [O3],[O4] [O6], [O11], [O12], [O13], [O17], [O18], [O20], [O21], [O22], [O23], [O24], [O25], [O26], and [O27]. The first step is to promote awareness among staff, and visitors of the potential EMI effects on devices. Equipment purchased should conform to appropriate EMC standards.

Device users should follow the manufacturer’s recommendations for avoiding EMI problems. Problems that occur should be reported to the appropriate regulatory authorities, including the FDA MedWatch system at www.fda.gov/medwatch.

The use of portable RF transmitters such as hand-held transceivers and cellular telephones in proximity to devices might need to be restricted or facilities might need to install in-house microcells to control the RF output power of handsets to keep it low. Facility engineers should become aware of the existence of and the operating characteristics of RF transmitters on the roof of the building and also those in the vicinity. Rooftop RF transmitters found to disrupt the performance of devices within the facility should be removed, if possible. If it is impractical to remove rooftop RF transmitters and if they are found to cause excessive device performance degradation, the susceptible devices should be replaced or relocated to other areas, or shielding of the area should be considered. However, shielding an area can result in problems if RF transmitters are allowed inside the shielded area (see discussion below). Until all devices in use meet minimum electromagnetic immunity standards, it might also be necessary to restrict the use in the immediate neighborhood of the facility of two-way radios, particularly mobile radios of moderate to high power such as those used by security, police and fire services, delivery services, shuttle busses, and taxis.

Whether or not a device meets minimum electromagnetic immunity standards, ensuring that the device (including cables, sensors, and electrical accessories) is not exposed to ambient RF fields that exceed its radiated RF immunity can help prevent interference problems. This can often be accomplished by maintaining physical separation between the device and RF transmitters. While the field strength to which a device is exposed can only be determined accurately by precise RF measurements, if the radiated immunity of a device and the rated output power of a transmitter are known, the minimum separation distance to be maintained between them to help prevent interference can be estimated within approximately a factor of ten.

In free space, in the far field (distance greater than several wavelengths of the transmitter carrier frequency), and for typical antennas, the field strength from a transmitter varies proportionally to the inverse of the distance from the transmitter. If the output power of a transmitter is known, the dipole equation (see [O10]) can be used to calculate an estimate of the field strength in the far field as a function of distance. If the radiated RF immunity of a device is known, substituting the immunity for the field strength and solving the dipole equation for distance yields the following:



where

P is the output power of the transmitter in watts (W);E is the immunity of the device in volts per meter (V/m);d is the minimum separation distance in meters;k is a constant in the range of 0.45 to 7, depending on the antenna efficiency of the transmitter.

The value of k for cellular telephones is approximately 7, and the value for lower-frequency hand-held transmitters such as walkie-talkies can be as low as 3 (see [O10]).

This approximation does not apply at distances less than several wavelengths of the transmitter carrier frequency (i.e., in the near field). Therefore, for medium-power RF transmitters that are normally hand-held, an appropriate minimum separation distance should be on the order of 0.5 m (20 in) to 1 m (39 in).

The limitations of this estimate are described below. The following is assumed:

A single transmitter is present, radiating at its maximum rated power; and the worst-case susceptibility of the device occurs at the frequency of the transmitter.

In addition, if multiple RF transmitters (e.g., cellular telephones) are in use, the actual minimum separation distance could be greater than that determined from the equation. If a single RF transmitter is radiating less than its maximum power rating or the worst-case susceptibility of the device occurs at a frequency other than that of the RF transmitter of interest, the actual minimum separation distance could be less than that determined from the equation.

The actual minimum separation distance is also affected by antenna efficiency and pattern and by absorption and reflection by buildings, objects, and people. Multipath reflections could result in an actual minimum separation distance that is greater than that determined from the equation, and absorption could result in an actual minimum separation distance that is less than that determined from the equation. If an RF transmitter is used in a shielded area that is not lined with adequate RF absorbing material, reflections within the shielding can result in areas of high field strength (see [O15]). In this case, Equation (F.1) should not be used.

Table F.1 presents some example free-space, far-field estimates for the case in which k = 7.

(F.1)



Table F.1 Example minimum separation distance estimates for k = 7a

Output power of RF transmitter

Immunity of device

0.1 V/m 3 V/m 10 V/m10 mW 7 m 0.25 mb 0.25 mb

100 mW 22 m 0.74 m 0.25 mb

600 mW 54 m 1.8 m 0.54 m2 W 99 m 3.3 m 1 m100 W 700 m 23 m 7 m

a. See previous discussion of the limitations of this estimation in this annex.b. See discussion of minimum separation distance in Clause 6.

EMC should also be considered in the design, site analysis, floor planning, and construction of facilities. Architectural EMC techniques should be used in the design and construction of the facilities (see [O25]). Power distribution should be designed to minimize conducted interference from high-power equipment. Potential sites under consideration for new facilities should be examined for proximity to high-power transmitting antennas, and an electromagnetic site survey should be made. Floor planning is important for both new and existing facilities, and units in which particularly sensitive devices are used, such as fetal heart monitors, electroencephalographs (EEGs), electromyographs (EMGs), and older apnea monitors, should not be located near areas where intense RF emissions can occur, including imaging systems, elevators, or electrosurgery suites. Attention should also be paid to equipment located on the floor above and below sensitive devices, as well as proximity to outside walls or drive-throughs that might be exposed to mobile two-way radios at close range. Some existing rooms might need to be shielded, in order to ensure proper operation of devices. However, if RF transmitters are used inside shielded rooms that are not lined with adequate RF absorbing material, increasing the separation distance could be ineffective and EMI problems could be worse than without the shielding.

In summary, organizations should

a) Consider using this in-situ test method to test potentially susceptible devices;b) Encourage managers and engineers to learn how to assess the electromagnetic environment of

their facility;c) Manage (increase) the distance between sources of electromagnetic disturbance and susceptible

devices (including cables, sensors, and electrical accessories);d) Manage (e.g., label, replace, or contact the manufacturer’s representative to determine if EMC

upgrades are available for) devices that are highly susceptible to EMI;e) Use the lowest output power necessary to accomplish the intended purpose for sources of

electromagnetic energy that are internal to the facility and are within the organization’s control;f) Implement systems to control the RF output power of in-house mobile phones and keep it low;g) Educate staff (including nurses and physicians) to be aware of, and to recognize, EMI-related

problems;h) Share relevant EMI/EMC information with others;i) Consider EMI when planning facility layouts;j) Consider EMC when purchasing new equipment;k) Educate staff about EMI problem recognition and mitigation; andl) Consider retaining the services of an EMC consultant for assistance in characterizing the

electromagnetic environment, solving specific problems, and/or educating staff.



Annex G

(informative)

Sample test data sheets



Annex H 1 Devices tested

Code Type Manufacturer Model Serial No. Age Why chosen?1

EMC claims?

Comments (Adjustable settings)

D1

D2

D3

D4

D5

D6

D7

D8

D9

D10

1 Reasons for selecting device for testing:a) The device is critical;b) The device has not been tested for compliance with applicable EMC standards;c) Failure or malfunction of the device could adversely affect plant operations;d) There are known EMC problems with similar devices due to insufficient RF immunity;e) RF transmitters are frequently used in the vicinity of the device (e.g., in emergency rooms);f) The device uses sensitive components or circuitry (e.g., circuits with high-gain amplifiers, sensor wires and cables, and microprocessors can be particularly sensitive);g) The device has been noted to perform erratically;h) The device is repeatedly referred for service, yet when the performance of the device is tested, no problem is found, particularly when tested in a service location which might be elsewhere in the building (e.g., the basement) or off-site;i) Other (explain).



H.1 2 RF WAVEFORMS USED DURING TESTING

Code Name Modulation Frequency Band (MHz)

Power (W) File Hash Code

Nominal test distance

T1

T2

T3

T4

T5

If an E-field meter is not used, record the method used to determine the test distances and transmit power.

Note: The appropriate personnel at the facility need to determine whether any observed interactions are acceptable or unacceptable and establish their own separation distance recommendations.



3 Test setup and test area configurationSketch the test setup and test area showing dimensions, objects in the room, windows, adjacent (sides, above and below) areas, location of the test device. Include photographs on separate pages.

Dimensions of area: m x m (also mark on drawing)

Adjacent areas include:



Comments:



4 Test setup checklist

Device ID ____

Device placement

___Table top ___Non conductive table

___80 cm high

___Floor standing ___Other height_______cm

Ancillary equipment placement

___simulators used

Describe those used including their location during testing

___sensors used

Describe location and connections from device under test to simulators

___Batteries fully charged

Device lead/cable arrangement

___Cables directed out the rear of DUT

___Cables coming out the front of the DUT routed over top towards rear

___Cables >3m long stretched out for the first 3m and then in a serpentine bundle

___Cables 40 cm off the floor

___Transition of cables from device to 40 cm height as short as possible



___Describe cable supports used

Comments:



5 Test Data

Device ID _____Device operating properly? _____

Description of device normal operating mode:

Transmitter ID _____ Batteries fully charged? _____

Minimum test distance _____m

Tx mode(Continuous,

keyed, talking, receiving a call, making a call,

standby)

Tx position(Label on setup

diagram)

Antenna(V, H,

alternating)

Height at which EMI occurs

m

Distance from DUT at which EMI ceases

m

Response(None, specific description, or code(s)

from table)

Do not approach closer than recommended minimum test distance before consulting applicable cautions. Comments:



Response Codes (for describing performance degradation):a) No change in operationb) Cessation of function without visible and/or audible alarmc) Cessation of function with visible and/or audible alarmd) Change in function or delivered therapy with alarme) Change in function or delivered therapy without alarmf) Reboot or power down with loss of datag) Reboot or power down without loss of datah) Manual reset required to continue operationi) Change in mode or operational state without alarmj) Change in mode or operational state with alarmk) Alarm malfunction or failure to alarml) Visible and/or audible alarm with continuation of functionm) Change in measured and/or displayed data with change in operationn) Change in measured and/or displayed data without change in operationo) Change in audio indicatorp) Distortion of displayed waveformsq) Display malfunctionr) Recorder malfunctions) Error message or service codet) Other (describe)



(normative)Illumination profile

This annex provides the minimum immunity required to claim compliance with this standard. A product shall first demonstrate an RF immunity of ≥ 10 V/m when tested using IEC 61000-4-3 or the near-field scanning method described in this document.a In addition, the EUT shall also meet the RF immunity levels specified in Table A.1 when tested using the procedures of this standard. Table A.2 lists the minimum test frequencies that shall be tested.

Higher levels of protection are required in the frequency bands allocated for mobile device transmission, which is the reason for the requirements of this annex.b Field experience or knowledge of particular issues in a specific type of environment may lead to applying additional requirements to assure adequate RF immunity in other bands.

The RF level is based on the CW signal before modulation is applied. After the proper RF exposure level is determined, the required modulation is applied for the test.

Table 6—Test modulation and field strengthc


Test modulation Field strength

(V/m)

Testmethod

824–849 Recreated Modulation pattern as in 5.1a

30 ANSI C63.9

1850–1915 Recreated Modulation pattern as in 5.1 a

30 ANSI C63.9

aThe modulation scheme used shall be recorded and justified in the test report.

Table 7—Standard test frequencies

StepFrequency

[MHz]Frequency

[MHz]1 824.00 1850.002 832.24 1868.503 840.56 1887.194 848.97 1906.065 N/A 1915.00

a IEEE Std 1309-2005 provides guidance on calibrating probes for use in determining field strengths. Probes calibrated to IEEE Std 1309-2005 can be used for both IEC 61000-4-3 and near field scanning. Further guidance on near field scanning is contained in ANSI C63.19.

b For the portion of the mobile phone bands allocated for use in the U.S. for the handset transmit channels an immunity of 30 V/m is recommended. For other bands, an immunity of 10 V/m is recommended, which is consistent with the IEC recommended immunity level for industrial equipment.

c The rows in the table identify the frequency bands of most interest. These bands historically have had the highest number of reported interference problems in field experience.



Annex I

(normative)

Test equipment specifications

I.1 General

Other than as specified in this document, the RF-test equipment, test configuration and test procedures as specified in IEC 61000-4-3 and IEC 61000-4-20 shall apply.

I.2 Analog phone DC feed circuit

IEEE Std 269 shall be followed for guidance on building and using an analog phone DC feed circuit.

The general-purpose DC feed circuit from IEEE Std 269 is shown in Figure I-8. Since the parameters of the feed circuit affect transmission performance, they should be recorded as part of the test setup. If available, parameters should be obtained from the applicable performance specification. If not, the following values should be used:

C 50 microfaradsL 5 henries (each)R = 400 Ω, including resistance of inductorsV = 50 voltsA = ammeter used to measure current drawn by the telephone under test. Alternatively, the current can be fixed by a current source, regardless of the R value.

In some cases, ground loops may occur when connecting test equipment to the receive electrical test point (RETP) or send electrical test point (SETP). The insertion of a high quality 1:1 audio transformer can usually prevent this. If used, this transformer shall be included during calibration and when determining the loss of the feed circuit.



Figure I-8—General purpose DC feed circuit for 2-wire analog telephone

I.3 Anechoic or semi-anechoic chamber

The anechoic or semi-anechoic chamber shall meet the field uniformity requirements of IEC 61000-4-3 and be of a suitable size to be able to maintain a calibrated field.

NOTE—Additional absorber may be required to damp any reflections in unlined chambers.

The isolation shall be sufficient to separate the test environment from the external environment. Shielding effectiveness shall be measured per IEEE Std 299-2006.

I.4 Antennas

Field generating antennas shall be capable of handling the power required to establish the field strengths required.

I.5 Planar dipoles

A planar dipole fabricated on a low loss printed circuit board, such as that shown in Figure I-9 and FigureI-10, may be used when testing to this standard. Such a dipole has the advantages of being readily implemented, very robust, and cost effective. The planar dipole is pictured in Figure I-9. Construction information is provided for a design in the drawing of Figure I-10, and Equation (B-1) should be used for other bands.



Figure I-9—Front and back sides of planar dipole

Figure I-10—Dimensions of dipole (in mm)



To adapt this design for other bands, the dipole arm length that determines the resonant frequency can be calculated using the Equation (B-1):

(B-1)

LFreespace = Length of dipole arm for tuning in freespace in mm. Shown as “L”.

An alternate form of the equation is:

(B-2)

In this form of the equation, ƒ is the frequency in MHz and LFreespace is again in mm.

For all frequencies above 700 MHz, the dimensions of the broadband balun (the tapered microstrip section) remains constant.a

I.6 Isotropic field probes

An isotropic field probe measuring system shall be capable of covering the frequency and power ranges required and be calibrated to IEEE Std 1309-2005.

I.7 RF signal generator

RF signal generators shall cover the frequency range required for the test. They shall have a bandwidth and sampling rate sufficient to recreate the recorded waveform or create it directly.

Power amplifiers shall be capable of providing modulated and unmodulated signals at the frequency and power required. Harmonics generated by the power amplifier shall be at least 15 dB below the carrier level.

I.8 Acoustic transmission line

Several methods are available for providing an acoustic transmission line from the EUT to the measurement instrumentation. Undamped transmission line commonly has unacceptably large variation in its transmission loss over frequency. Adding a 1500 Ω damper is recommended to significantly smooth the loss response as a function of frequency. A 1 m damped acoustic transmission line, commonly called a damped “long horn,” is recommended for larger separations. This device is constructed of 600 mm of 2 mm tubing that connects to the EUT. At the end away from the EUT, a 680 Ω damper is inserted to smooth the transition to a 400 mm length of 3 mm tubing. At the end of the 3 mm tubing, a 330 Ω is inserted and transitions to an 18 mm length of 4 mm tubing. The 4 mm tubing then connects to the ear coupler and measurement instrumentation (see Figure B.4).a Richard, M., M. Kanda, G. Bit-Babik, C. DiNallo, CK Chou. A Rugged Microstrip Printed Dipole Reference for SAR System Verification. 2002 IEEE MTT-S International Microwave Symposium, Seattle, WA. June 2–7, 2002.



Figure B.I-11—Construction of 1 m damped "Long Horn" acoustic transmission line



Annex J

(normative)

Recording waveforms

J.1 IQ recordings

RF signals can be received, recorded, and recreated in a number of ways. Converting RF signals to a digital format for storage and recreation has a number of advantages. Vector signal analyzers and generators typically store and recreate RF signals using in-phase and quadrature (IQ) data format.

The IQ format records a real and imaginary component for each sample of the RF signal. IQ data can be conceived using the mathematical concept of a complex plane, which is represented geometrically by a real axis and an orthogonal imaginary axis. The real part of a complex number can be represented by a displacement along the x-axis, and the imaginary part by a displacement along the y-axis. This complex plane is sometimes called the Argand plane, named after Jean-Robert Argand. Any complex number can be represented using this complex plane. For RF waveforms it means that any waveform, no matter how complex, can be accurately represented using IQ values.

Vector signal generators and analyzers use a process called quadrature digital upconversion or downconversion, respectively. I and Q pairs are recorded or input to recreate the recorded signal. The recording is the baseband representation of the signal and the upconversion or downconversion move the baseband signal to its RF carrier frequency or extracts the baseband signal from the carrier frequency.

The sample rates of the IQ data must meet the Nyquist requirement of being at least twice the bandwidth of the baseband signal.

J.2 Data file structure

Data files for recorded RF signals have three logical components. There is no single standard industry recognized format. It is therefore helpful to record data files in a way that supports conversion to alternate formats. Many manufacturers of vector instruments provide conversion utilities.

Using a file format that can be easily read and converted by a wide variety of users is very helpful. Text files meet this criterion, but they can be difficult to manipulate. XML is another alternative that is easily read by a wide variety of users but is more amenable to manipulation and data conversion.

The data file has three logical components. The first is the metadata, the information about the information in the file, its structure and the types of the data elements in the file. The second component is the information about the recording, what was recorded, the type of signal being recorded, the original carrier frequency, the sampling rate and other useful information. The third component is the actual IQ data.

Data files following these guidelines allow for conversion to a variety of formats and use in vector instruments from different manufacturers.

The following provide a few guidelines (not requirements) to be considered when selecting a file format:



While metadata is not required it is strongly encouraged because of the value it provides.

It is helpful if the Metadata is in ASCII, and may be either included in the file, or a separate file. Separate files probably work better if the IQ vectors are stored in binary format, but of course a single file means that the metadata cannot become separated from the IQ vectors.

Metadata includes the following:

a) The length of the metadata. This would be especially helpful if the metadata was included in the same file as the IQ vectors.

b) IQ Data format (i.e., Is the data is stored as I,Q,I,Q… or I,I…,Q,Q…?)

c) Type of delimiters (such as a comma between ASCII values)

d) Sample rate

e) What units the IQ data are stored as. Some possibilities for this include:

Normalized (no units) to an arbitrary value

Constellation units (another form of normalization)

Volts (and related, such as mV)

Undefined (not normalized to anything specific)

Other metadata is allowed, such as the RF center frequency

It is recommended that IQ vectors be stored as ASCII, or IEEE floating point values (either 4 byte or 8 byte versions).



Annex K

(informative)

Comparison of test methods

This annex provides a discussion comparing and contrasting the different methods of RF illumination allowed in this standard (see Table 8). This material may prove helpful in selecting the appropriate alternate method of RF illumination for a particular EUT.

Table 8—Test method comparison

Near-field illumination

Anechoic or Semi-anechoic

chamber

GTEM

Test positionsfor complete evaluation

Surface survey of four sides and top

of EUT

≥3 ≥3

Field uniformity Highly variable –0 to +6 dB –0 to +6 dB

Required RF power Low High Moderate

Typical test time Variable 4 h to 12 h 2 h to 4 h

If the EUT is tested in accordance with IEC 61000-4-3 at 3 V/m or 10 V/m the additional time in either a semi-anechoic chamber or GTEM can be estimated as follows: 10 Frequencies × 1 minute dwell time × 2 antenna polarizations (V/H) × 4 EUT sides, which amounts to about 80 minutes.



Annex L

(informative)

Testing of mobile phone headsets

Headsets and similar accessories that are intended to be directly connected to mobile transmitters are often subjected to higher levels of RF exposure than most other types of office equipment. This annex suggests elevated field strengths to use when evaluating these devices (see Table 9).

L.1 Field strength

Table 9—RF field strength requirementsa

Equipment category Field strength(V/m)

Cellular TX Band824 – 849 MHz

90

PCS TX Band1850 – 1920 MHz

90

a Headsets, particularly those with physical cables connecting them to a transmitter, will often have RF coupled onto the cable and transmitted to potentially sensitive circuitry. Hence, higher levels of immunity are recommended.



Annex M

(informative)

RF Immunity—Frequency range and field strength

M.1 Use scenario

This standard has been written with a primary focus on the typical home and office environments. It is recognized that there are other use scenarios and types of environments. Also, some homes and offices represent extreme cases in various ways. It was the intent of the committee to provide recommendations that would give high levels of protection for most common types of home and office environments. The utility of this standard for use scenarios and environments that are significantly different is left to the judgment of the engineer responsible for providing protection to such environments.

M.2 Frequency range

The rationale for the frequency ranges selected in this standard is based on the spectrum assignment of the frequency bands and how commonly the transmitters in the various services can be found operating near office equipment in typical home or office environments.

The committee concluded that the most common interference situation was cell phones in either the traditional cellular band or the PCS band transmitting near office equipment. Accordingly, the handset’s transmit bands for those devices are set apart for special protection.

The committee realizes that there are both other common transmitters and more powerful transmitters in use. However, the coincidence of these other classes of devices being used in close proximity to office equipment was judged to be significantly less frequent.

M.2.1 U.S. cellular system

This subclause presents the U.S. cellular system frequency plan. For the purposes of this document, high levels of immunity are required in the spectrum regions allocated for mobile device transmission. It is in these frequency bands that mobile devices have the potential for creating high field strengths in close proximity to office equipment.

M.2.2 CMRS bands in the U.S.

In the U.S. most commercial mobile radio services (CMRS) are provided through systems operating in the 800 MHz and 1900 MHz bands. These bands are commonly called the cellular bands for 800 MHz and the personal communications services (PCS) band, for the 1900 MHz service (see Figure M-12 and Figure M-13). Each band is broken into blocks with paired transmit and receive frequencies, separated by a guard band. Through auctions, licenses have been assigned to service providers for each block in the various geographic areas of the U.S.

These bands are regulated by the Federal Communications Commission (FCC) under FCC Part 22 (47CFR22) for the cellular band and FCC Part 24 (47CFR24) for the PCS band. To a lesser but important degree, FCC Part 90 (47CFR90), private land mobile services, are also used.



New spectrum has been identified and the service rules are currently being written by the FCC for third generation cellular networks. These services are being called Advanced Wireless Services (AWS) by the FCC (see Figure M-14). A major feature of AWS services is that they are designed to provide high voice/data integration and support many enhanced data services. As third generation networks are deployed, transmitting data of the type contemplated in this report will become increasingly easy. An important criterion in selecting a solution is to assure that the solution adopted will seamlessly move one third generation networks as they are deployed.

Figure M-12—Band plan for U.S. cellular banda

Figure M-13—Band plan for U.S. PCS bandb

Figure M-14—Band plan for U.S. AWS Band

a In the lower frequencies, 824–849 MHz, the handset is transmitting and the base station is receiving. Therefore, this frequency range is of particular interest for this standard.

b In the lower frequencies, 1850–1915 MHz, the handset is transmitting and the base station is receiving. Therefore, this frequency range is of particular interest for this standard.



M.3 New and emerging services

Several new services are in the process of being approved or deployed. Table F.1 lists those of most interest for this standard.

Table 10—New services

Band Frequency Transmit power

Service

Land Mobile 698–746, 747–762, and 777–792 MHz Bands

3 W Mobile / Fixed

Advanced Wireless Services |(AWS)

1710–1755 MHz 1 W Mobile (IMT / 3G)

Advanced Wireless Services |(AWS)

2155–2175 MHz 1 W Mobile (IMT / 3G)

Mobile 2.5–2.689 GHz 2 W Mobile (IMT/3G)

Land Mobile 3650–3700 MHz 1 W/25 MHz Broadband wireless

Land Mobile 4940–4990 MHz 2 W Public safety

M.4 Field strength

This standard has been prepared to provide protection from mobile transmitters of up to 8 watts of RF power. The committee selected ~30 cm (approximately 1’) as a target protection distance for cell phones and ~70 cm (approximately 2.5’) as a target protection distance for 8 watt transmitters (see Table F.2).

Table 11—Calculated field strengths from a dipole radiator

An immunity of 30 V/m has proven to be generally effective in providing the protection from RF interference desired.



Annex N

(informative)

RF Immunity—Modulation characteristics

Previous immunity standards have specified testing with the RF carrier modulated with 1 kHz AM. With advancements in modern communications equipment and the increased population density of portable RF transceivers, simple tone modulation immunity testing has proven not to simulate actual performance. This increased difference in laboratory test results and application performance can be explained by the nature of the modulation characteristics.

N.1 Modulation characteristics of radio servicesThese modulations are a selection of the dominate or most interfering modulations used in each frequency band (see Table G.1).

Table 12—Modulations used by different radio services


Modulationcharacteristics

Common services

Service Modulation Typical power(W)

698–915 Pulse Modulation with 217 Hz repetition rate and 1/8 duty cycle

GSM

GPRS

EDGE

TDMA with GMSK, 8PSK

2

iDEN TDMA with 2

915–1710 Various Various other services

1710–1980 Pulse Modulation with 217 Hz repetition rate and 1/8 duty cycle

GSM

GPRS

EDGE

TDMA with GMSK, 8PSK

1

CDMA 2000

1xRTT

EV-DO

DSSS, QPSK 1

UMTS3GPP w/ HSDPA

WCDMA, BPSK 1

Various other services




Modulationcharacteristics

Common services

Service Modulation Typical power(W)

1980–2400 Various

2400–2475 Various ISM Band FHSS, DSSS 1

Bluetooth® FHSS, GMSK .01

WiFi DSSS, CCK, OFDM .1

WiMAX BPSK, QPSK, 16QAM, 64QAM

.1

2475–3650 Various

UWB DS & OFDM

Various other services

3650–3700 OFDM WiFi DSS, CCK, OFDM


4940–4990 OFDM





5850–5900 Various WiFi DSS, CCK, OFDM .1


.1

5900–6000 Various

N.2 Amplitude modulation

In amplitude modulation (AM) systems, the modulation audio is applied to the transmitter radio frequency carrier such that the total power of the transmitted signal is varied directly as the power of the modulating signal.



For example, with a carrier of 10V/m and 80% modulation of 1 kHz, the peak-to-peak voltage of the transmitted modulated wave is given by Equation (G-1).

Vpk – pk(mod) = modulation depth × Vpk – pk(unmodulated) + Vpk – pk (unmodulated) (G-1)

Therefore:

Vpk – pk(mod) = 80% × 10V/mpk – pk(unmodulated) + 10V/mpk – pk (unmodulated) = 18 V/m

or a 5.1 dB increase over the CW.

Modulation at 80% increases the instantaneous power requirement by a factor of 5.1 dB. This means that the RF power amplifier used to produce the transmitted wave should be overrated by about 6 dB.

In addition, the spectrum of a purely modulated AM signal would consist of the carrier frequency at constant amplitude with an upper and lower sideband signal spaced ±1 kHz from the carrier and varying at a sinusoid 1 kHz rate. Ideally no other frequency components would be present. However, in practice the circuitry in RF equipment has non-linear transfer characteristics. This results in added sideband components and a reduction of the amplitude of the signals at ±1 kHz since the total modulation power has not changed. Thus if only the 1 kHz component is measured for the immunity testing, the effects of RF power amplifier non-linearity is to reduce the effective modulation index for the 1 kHz tone.

N.3 Pulsed amplitude modulationIn pulse modulation (PM) systems, the modulation is applied to the transmitter radio frequency carrier such that the total power of the transmitted signal is a direct function of the effective duty cycle of the pulse envelope. The RF spectrum of a pulse modulation system would consist of a complex set of RF components about the carrier frequency. For example, with a 100 Hz pulse rate and 100 μs pulse duration, the RF components are spaced every 100 Hz above and below the carrier with a sine X/X amplitude function. The first amplitude null would occur at 1/tp or the duration of the pulse or 10 kHz. That is, the RF components would have about the same amplitude over a 5 kHz bandwidth around the center frequency. However, significant spectral components can extend well into the 100s of kHz.

An effect of complex RF spectrum energy radiation on systems is that demodulated RF components above and below the audio band may permeate throughout the system because of non-ideal filtering components and multiple clock signals within the system. Thus the lower demodulated frequencies may pass from section to section because of internal series resistance of bypass capacitors and printed circuit board trace resistance. The higher demodulated frequencies can pass from section to section because of mutual inductance of the printed circuit traces and sympathetic pulling and mixing of system oscillators.



Annex O

(informative)

Bibliography

[O1] ANSI/TIA-631-A-2002, Telecommunications—Telephone Terminal Equipment—Radio Frequency Immunity Requirements. a

[O2] IEEE 100™, The Authoritative Dictionary of IEEE Standards Terms, Seventh Edition.b, c

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[O4] ISO Technical Report #21730 - 2006, Health informatics — Use of mobile wireless communication and computing technology in facilities — Recommendations for electromagnetic compatibility (management of unintentional electromagnetic interference) with devices

[O5] ANSI C63.12-1997, American National Standard Recommended Practice for Electromagnetic Compatibility Limits.

[O6] CISPR 24:2010 Ed. 2.0, Information technology equipment—Immunity characteristics—Limits and methods of measurement.

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[O12] IEC 61000-5-2 (1997), Electromagnetic compatibility (EMC)—Part 5: Installation and mitigation guidelines—Section 2: Earthing and cabling.

a ANSI publications are available from the Sales Department, American National Standards Institute, 25 West 43rd Street, 4th Floor, New York, NY 10036, USA (http://www.ansi.org/).

b The IEEE standards or products referred to in this clause are trademarks of the Institute of Electrical and Electronics Engineers, Inc.

c IEEE publications are available from the Institute of Electrical and Electronics Engineers, 445 Hoes Lane, Piscataway, NJ 08854, USA (http://standards.ieee.org/).



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[O27] Witters, D., “Devices and EMI: The FDA Perspective,” ITEM Update, 1995, pp. 22–32.

